The following is a timeline of the COVID-19 pandemic in the Republic of Ireland in 2021.

Timeline January 2021 2 January A further 3,394 cases and 4 deaths were reported, bringing the totals to 96,926 cases and 2,252 deaths. It was revealed that there were approximately 9,000 positive COVID-19 tests not yet logged on the HSE's IT systems, due to both limitations in the software; and lack of staff to check and input details, meaning there was an effective ceiling of approximately 1,700 to 2,000 cases that could be logged each day. The Director of the National Virus Reference Laboratory Cillian de Gascun announced that a further nine cases of the UK variant of COVID-19 had been detected in the Republic of Ireland from 23 December to 29 December, bringing the total number of cases identified to 16. 6 January A further 7,836 cases and 17 deaths were reported, bringing the totals to 121,154 cases and 2,299 deaths. 4 previously notified cases were de-notified. The Government agreed a number of new lockdown measures including the closure of all schools until February with Leaving Certificate students allowed to attend school for three days a week, the closure of all non-essential construction sites with certain exceptions, the requirement for all passengers from the United Kingdom and South Africa to have a negative PCR test and the prohibition of click-and-collect services for non-essential retail. It was announced that Minister for Justice Helen McEntee tested positive for COVID-19. 7 January The government was forced to abandon plans for Leaving Certificate students to attend school on three days a week, and instead students would return to homeschooling until February, after the ASTI directed its members not to return to in-school teaching. The rollout of the Pfizer–BioNTech COVID-19 vaccine in private and voluntary nursing homes began nationwide, with 22 nursing homes of 3,000 residents and staff to be vaccinated. 8 January A further 8,248 cases and 20 deaths were reported, bringing the totals to 135,884 cases and 2,327 deaths. 21 previously notified cases were de-notified. In a statement from NPHET, Chief Medical Officer Tony Holohan confirmed that three cases of the South African variant of COVID-19 had been detected in the country by whole genome sequencing associated with travel from South Africa. 11 January Figures revealed by the Our World in Data organisation showed that Ireland had the highest daily number of new confirmed COVID-19 cases in the world for every million people. Gardaí received new COVID-19 enforcement powers, including the power to fine people €100 in breach in the 5 km travel limit. 12 January The government agreed that all passengers arriving into Ireland would need a negative PCR COVID-19 test taken 72 hours before departure from Saturday 16 January. The first shipment of the Moderna vaccine arrived in the Republic of Ireland. 15 January – The Chief Medical Officers of Ireland and Northern Ireland Tony Holohan and Michael McBride issued a joint statement urging everyone to stay at home. 17 January – The government requested early deliveries of the Oxford–AstraZeneca COVID-19 vaccine as discussions to secure early delivery of the vaccine got underway. 18 January – The number of patients with COVID-19 being treated in hospitals around the country reached a record 2,023, with 200 in ICUs and over 400 people receiving high-grade ventilation and respiratory support. 19 January – The government was forced to abandon plans to reopen special schools on 21 January for thousands of children with special educational needs following safety concerns among staff unions. 20 January – The St Patrick's Day parade in Dublin was cancelled for a second year. 22 January – Chief Clinical Officer of the HSE Colm Henry stated that COVID-19 transmission levels remained too high for schools to reopen in February. 26 January – The government announced the extension of the Level 5 lockdown restrictions until 5 March, along with a number of new measures including a mandatory 14-day quarantine period for all people travelling into the country without a negative COVID-19 test. 30 January – Chief Medical Officer Tony Holohan announced that more cases had been confirmed in one month than throughout 2020 with over 1,000 deaths and more than 100,000 cases confirmed in January. 31 January – A further 1,247 cases and 15 deaths were reported, bringing the totals to 196,547 cases and 3,307 deaths. 3 previously notified cases were de-notified.

February 2021 1 February – The Department of Education agreed to reopen special schools with 50% capacity on 11 February and special classes in mainstream schools on 22 February. 3 February – The Department of Public Health expressed concern over increases in COVID-19 transmission linked to social gatherings involving the student population in the mid-west region. 4 February – The total number of COVID-19 cases in Ireland surpassed 200,000 cases, with over half confirmed in 2021. 6 February – The first shipment of 21,600 AstraZeneca vaccines arrived in the Republic of Ireland. 10 February – The World Health Organization praised Ireland's recovery from the third wave of COVID-19 but warned of the danger of a fourth wave. 11 February – The ASTI withdrew from discussions with the Department of Education on the Leaving Certificate 2021 after it said that the plan being developed would not provide a "meaningful Leaving Certificate" for students. 12 February – It was confirmed that the traditional St Patrick's Day meeting between US President Joe Biden and Taoiseach Micheál Martin at the White House would take place virtually due to the COVID-19 pandemic. 13 February – The ASTI re-joined discussions with the Department of Education on the Leaving Certificate 2021 after pulling out on 11 February. 15 February – Minister for Health Stephen Donnelly confirmed locations for 37 vaccination centres across all counties as part of the country's COVID-19 vaccination programme. 17 February Ireland's COVID-19 death toll surpassed 4,000 as Deputy Chief Medical Officer Ronan Glynn announced that 90% of COVID-19 cases in Ireland were the UK variant of COVID-19. Minister for Education Norma Foley confirmed that Leaving Certificate examinations would proceed with students given the option between a modified version of calculated grades or written exams, while Junior Certificate examinations were cancelled for a second year in a row. 19 February – Taoiseach Micheál Martin expressed his condolences to Chief Medical Officer Tony Holohan and his family after his wife, Emer, died following a long illness with multiple myeloma. 22 February – Special classes in mainstream primary and secondary schools reopened as the phased reopening of schools continued. 23 February – Taoiseach Micheál Martin announced the extension of Level 5 lockdown restrictions for another six weeks until 5 April at the earliest as the government published its new revised Living with COVID-19 plan called "The Path Ahead", which included the phased reopening of schools and childcare and the extension of the COVID-19 Pandemic Unemployment Payment and the Employment Wage Subsidy Scheme.

COVID-19 Resilience and Recovery 2021 – The Path Ahead

27 February – 23 people were arrested and 3 Gardaí were injured (including one hospitalised), as around 500 protesters took part in an anti-lockdown protest in Dublin city centre, with fireworks being fired at Gardaí, while St Stephen's Green and the Iveagh Gardens closed in advance of the protest. The protest was widely condemned by the gardaí and politicians, including the Taoiseach, Tánaiste and Minister for Justice. 28 February A further 612 cases and 6 deaths were reported, bringing the totals to 219,592 cases and 4,319 deaths. Ireland officially marked one year since the first case of COVID-19 in the country was confirmed on 29 February 2020. 13 people, including 12 men and 1 woman, were charged and remanded in custody for public order offences after anti-lockdown protests in Dublin city centre turned violent on 27 February, while Tánaiste Leo Varadkar stated that the violence on the streets of Dublin was "not a protest and was a riot".

March 2021 1 March – Over 320,000 junior primary school pupils and Leaving Certificate students nationwide returned to school for the first time since Christmas. 2 March – A man in his 30s was arrested in connection with a firework attack on Gardaí at a violent anti-lockdown protest in Dublin city centre on 27 February. 3 March – Jake Merriman, a 30-year-old man, appeared in court charged in connection with a firework attack on Gardaí at an anti-lockdown protest in Dublin city centre on 27 February. 6 March Taoiseach Micheál Martin announced that Ireland had reached the milestone of half a million COVID-19 vaccines administered. Gardaí arrested 6 people (5 men and 1 woman) as around 450 people attended an anti-lockdown protest in Cork city centre that ended without incident. 7 March – President Michael D. Higgins signed into law the legislation to bring in mandatory hotel quarantine for certain passengers entering the country from high-risk countries. 11 March – Ireland officially marked one year since the first death of COVID-19 in the country was confirmed on 11 March 2020, the same day when COVID-19 was declared a pandemic. 14 March – The administration of the AstraZeneca COVID-19 vaccine was suspended in Ireland by the National Immunisation Advisory Committee (NIAC) as a precautionary measure following concerns over serious blood clots in Norway. 15 March – Over 350,000 remaining primary school pupils and fifth year secondary students nationwide returned to school for the first time since Christmas. 16 March – The Garda Síochána urged people to stay at home for St Patrick's Day as a significant policing operation was put in place to deal with planned protests in Dublin city with 2,500 Gardaí being deployed across the country. 17 March – Gardaí arrested 21 people after around 700 protestors took part in a number of anti-lockdown protests in Dublin city centre, Herbert Park and at the RTÉ campus in Donnybrook. 18 March – It was confirmed that 7 Gardaí were injured (including five hospitalised) after being kicked, punched and spat at in separate violent anti-lockdown protests which took place in Dublin on St Patrick's Day. 19 March – The NIAC recommended that the AstraZeneca COVID-19 vaccine could continue to be used in Ireland following approval from the European Medicines Agency (EMA) on 18 March. 23 March – The booking portal for mandatory hotel quarantine in Ireland opened for those arriving into the country from Friday 26 March, with a 12-night stay for passengers arriving from high risk countries costing €1,875 each. 26 March Ireland's mandatory hotel quarantine system for all passengers arriving into the country from high-risk countries came into force at 4 am. The Leader of the Labour Party Alan Kelly called for the chief executive of the Beacon Hospital to resign after it gave 20 leftover COVID-19 vaccines to a number of teachers and staff at a private secondary school in Bray, County Wicklow on 23 March. 27 March – Gardaí began an investigation after three people absconded from a mandatory hotel quarantine facility near Dublin Airport while on a smoking break outside under supervision, with one person located. 28 March – A second person who absconded from a mandatory hotel quarantine facility on 27 March was located, while a search for the third male continued. 30 March – The government announced a phased easing of Level 5 restrictions from 12 April, with people allowed to travel within their county, two households allowed to meet socially outdoors, fully vaccinated people allowed to meet other vaccinated people indoors, and the resumption of all residential construction projects from that date. From 19 April: Elite-level senior GAA matches and training could resume