Suffolk County Transit operates numerous bus routes in Suffolk County, New York, United States; a few in the town of Huntington are operated by Huntington Area Rapid Transit. The Villages of Patchogue and Port Jefferson, also have had their own local jitney bus routes, although budget cuts have forced these villages to take its buses out of service. Some of them are descendants of streetcar lines (see List of streetcar lines on Long Island).

The following tables give details for the routes that primarily service Suffolk County. For details on routes that run into Suffolk County but do not service it primarily, see:

List of bus routes in Nassau County, New York: n54, n55, n70, n71, n79

Suffolk County Transit (SCT)

On October 29, 2023, Suffolk Transit introduced the Reimagine Transit Initiative, a full redesign of the bus network. As part of this redesign, there is daily service system-wide with local buses running weekdays until 10 p.m. and to 8 or 9 p.m. on weekends.

All current routes

Most routes west of Port Jefferson and Patchogue are scheduled with 30 minute headways (60 minutes on routes 3, 10 and 15) during weekdays until at least 6:00 p.m. On all routes from Port Jefferson and Patchogue and to the east, including the north-south routes between those two terminals, there are 60-minute headways (except for 30-minute headways on routes 51 and 66). All weekday late evening and weekend service runs on 60-minute headways. Route numbers (not including 110) are lower in the western portion of the county (1 through 17) and higher in the middle and eastern portions (51 through 92). Odd-numbered routes are generally oriented north to south, with even numbers west to east. Timed connections between routes can be made at Long Island Rail Road stations in Amityville, Bay Shore, Brentwood, Central Islip, Patchogue, and Riverhead, and at the Smith Haven Mall.

SCT also runs two on-demand systems on the South Fork in Southampton and in East Hampton operated by Hampton Jitney and Via Transportation that replaced the former 10A, 10B, and 10C bus routes. The two on-demand zones connect with Route 92 in Southampton, Sag Harbor, and East Hampton. The zones operate 7 days a week between 6 AM and 8 PM, including holidays.

In early June 2024, SCT added a new route, the 56, running between Smithtown Railroad and Kings Park Manor.

In the following table, routes highlighted in red have 30-minute service on weekdays, with non-highlighted routes having 60-minute service. RouteTerminals Major streets servedNotes1https://sctbus.org/portals/32/Schedules/Route%201.pdf 1 schedule AmityvilleLIRR station↔HalesiteFirehouse Broadway (Amityville), Broad Hollow Road, Walt Whitman Road, New York AvenueDirectly serves SUNY Farmingdale and Walt Whitman Shops. LIRR connections: Amityville, Huntington2https://sctbus.org/portals/32/Schedules/Route%202.pdf 2 schedule↔PatchogueLIRR stationMontauk Highway Directly serves South Shore University Hospital. LIRR connections: Amityville, Babylon, Bay Shore, Oakdale, Patchogue3https://sctbus.org/portals/32/Schedules/Route%203.pdf 3 scheduleBabylonLIRR station↔South HuntingtonWalt Whitman ShopsBelmont Avenue, Deer Park Avenue, Carman Road, New York AvenueDirectly serves Five Towns College in Dix Hills. LIRR connections: Babylon, Wyandanch4https://sctbus.org/portals/32/Schedules/Route%204.pdf 4 schedule AmityvilleLIRR station↔Lake GroveSmith Haven MallStraight Path, Grand Boulevard, Suffolk Avenue, Nichols RoadServes Tanger Outlets in Deer Park along Grand Boulevard. LIRR connections: Amityville, Wyandanch, Deer Park, Brentwood, Central Islip5https://sctbus.org/portals/32/Schedules/Route%205.pdf 5 scheduleBabylonLIRR station↔Deer Park Avenue, Suffolk Avenue, Middle Country RoadDirectly serves State Office Building in Hauppauge. LIRR connections: Babylon, Deer Park, Brentwood, Smithtown6https://sctbus.org/portals/32/Schedules/Route%206.pdf 6 scheduleSouth HuntingtonWalt Whitman Shops↔PatchogueLIRR stationJericho Turnpike, Veterans Memorial HighwayDirectly serves State Office Building and North County Complex in Hauppauge and MacArthur Airport. LIRR connections: Central Islip, Patchogue7https://sctbus.org/portals/32/Schedules/Route%207.pdf 7 scheduleBay ShoreLIRR station↔NorthportVA Medical CenterBrook Avenue, Crooked Hill Road, Larkfield RoadDirectly serves South Shore Mall and Suffolk County Community College Grant Campus. LIRR connections: Bay Shore, Brentwood, Northport10https://sctbus.org/portals/32/Schedules/Route%2010.pdf 10 scheduleAmityvilleLIRR station↔ BabylonLIRR stationAlbany Avenue, Farmingdale Road, Albin Avenue, Montauk HighwayDirectly serves Great South Bay Shopping Center in West Babylon. LIRR connections: Amityville, Lindenhurst, Babylon11https://sctbus.org/portals/32/Schedules/Route%2011.pdf 11 scheduleBay ShoreLIRR station↔HauppaugeState Office BuildingBrentwood Road, Broadway (Brentwood), Washington Avenue, Oser Avenue Directly serves South Shore University Hospital. LIRR connections: Brentwood, Bay Shore12https://sctbus.org/portals/32/Schedules/Route%2012.pdf 12 scheduleEast FarmingdaleFarmingdale State College↔Bay ShoreLIRR stationColonial Springs Road, Nicolls Road, Bayshore RoadLIRR connections: Wyandanch, Bay Shore15https://sctbus.org/portals/32/Schedules/Route%2015.pdf 15 schedule BabylonLIRR station↔Robert Moses State ParkParking Field 3Montauk Highway, Robert Moses CausewaySummer daytime service only. In 2025, operates daily from June 16 until September 1. No early a.m. service. Directly serves Captree Fishing Basin on all trips. Directly serves Good Samaritan University Hospital. LIRR connections: Babylon17https://sctbus.org/portals/32/Schedules/Route%2017.pdf 17 scheduleEast IslipMontauk Highway and Carleton Avenue↔HauppaugeState Office BuildingCarleton Avenue, Lowell Avenue, Hawthorne Avenue, Veterans Memorial HighwayDirectly serves county and federal courts. LIRR connections: Central Islip51https://sctbus.org/portals/32/Schedules/Route%2051.pdf 51 schedulePatchogueLIRR station↔Port JeffersonShopping PlazaPatchogue-Holbrook Road, Hawkins Avenue, New York State Route 347, Nicolls Road, Broadway (Port Jeff)Directly serves Smith Haven Mall in Lake Grove and Stony Brook University. LIRR connections: Patchogue, Ronkonkoma, Stony Brook, Port Jefferson52Ahttps://sctbus.org/portals/32/Schedules/Route%2052A.pdf 52A scheduleCentral IslipLIRR station↔Gordon HeightsHawkins Avenue and Rose Laneat Gordon Heights Fire DepartmentAll trips: Veterans Highway, Motor Parkway, Ocean Avenue, Hawkins Avenue, Portion Road, 52A trips: Mooney Pond Road, Coram Plaza 52B trips: Horseblock Road, Granny RoadRoute 52B weekday daytime service only. Alternate buses serve each route, with each route switching to the other at the Gordon Heights terminal for service back to Central Islip. Routes shared to Suffolk County Community College Ammerman Campus in Selden.

LIRR connections: Central Islip, Ronkonkoma52Bhttps://sctbus.org/portals/32/Schedules/Route%2052B.pdf 52B schedule↔53https://sctbus.org/portals/32/Schedules/Route%2053.pdf 53 schedulePatchogueLIRR station↔Port JeffersonShopping PlazaWaverly Avenue, Boyle Road, Terryville RoadDirectly serves Suffolk County Community College Ammerman Campus, College Plaza.

LIRR connections: Patchogue55https://sctbus.org/portals/32/Schedules/Route%2055.pdf 55 schedule↔Medford Avenue, Patchogue-Port Jefferson Road, Patchogue RoadDirectly serves Coram Plaza.

LIRR connections: Patchogue, Medford56https://sctbus.org/portals/32/Schedules/Route%2056.pdf 56 scheduleSmithtownLIRR station↔Kings Park ManorNew York State Route 25 Weekday mid-day service only. Directly serves Siena Village and Saint Catherine of Siena Hospital. LIRR connections: Kings Park, Smithtown58https://sctbus.org/portals/32/Schedules/Route%2058.pdf 58 scheduleBrentwoodLIRR station↔RiverheadLIRR stationSuffolk Avenue, New York State Route 347, New York State Route 25, Middle Country RoadDirectly serves Smith Haven Mall in Lake Grove and Coram Plaza. LIRR connections: Brentwood, Riverhead62https://sctbus.org/portals/32/Schedules/Route%2062.pdf 62 scheduleHauppaugeState Office Building↔ New York State Route 347, New York State Route 25A, Middle Country RoadDirectly serves Smith Haven Mall in Lake Grove, Stony Brook Technology Center and Mather Hospital. LIRR connections: Port Jefferson, Riverhead66https://sctbus.org/portals/32/Schedules/Route%2066.pdf 66 schedulePatchogueLIRR station↔Main Street (Patchogue), Montauk Highway, Wiiliam Floyd Parkway, Mastic Road, Moriches-Riverhead RoadDirectly serves Suffolk County Community College Eastern Campus. Riverhead-bound trips serve Peconic Bay Medical Center. LIRR connections: Patchogue, Bellport, Mastic-Shirley, Riverhead77https://sctbus.org/portals/32/Schedules/Route%2077.pdf 77 schedule↔ BellportSouth Country Road and Woodruff StreetAll trips: Montauk Highway, Sills Road, 77 trips: Station Road 77Y trips: Horseblock Road, Yaphank AvenueRoute alternately shared during weekday peak hours with route 77Y to North Bellport. Directly serves Long Island Community Hospital. LIRR connections: Patchogue, Bellport77Yhttps://sctbus.org/portals/32/Schedules/Route%2077Y.pdf 77Y schedule↔East Yaphank The Boulevard Weekday rush hour service only. Route alternately shared with route 77 to North Bellport. Directly serves Long Island Community Hospital and Suffolk County Probation. LIRR connections: Patchogue80https://sctbus.org/portals/32/Schedules/Route%2080.pdf 80 scheduleRiverheadLIRR station↺Riverhead Circulator Counter-clockwise loop:Northville Turnpike, Old Country Road, River Road, Nugent DriveCounter-clockwise direction only. Directly serves Peconic Bay Medical Center, John Wesley Village, Tanger Outlets Riverhead, Calverton Hills. LIRR connections: Riverhead92https://sctbus.org/portals/32/Schedules/Route%2092%20Winter.pdf 92 Winter schedulehttps://sctbus.org/portals/32/Schedules/Route%2092%20Summer.pdf 92 Summer scheduleOrient PointFerry dock↔East HamptonLIRR stationMain Road, Main Street (North Fork), North Road, Bridgehampton-Sag Harbor Turnpike, East Hampton-Sag Harbor TurnpikeWinter schedule from November to April, otherwise summer schedule. Longest local bus route in the Northeastern United States at over . LIRR connections: Riverhead, Hampton Bays, Southampton, East Hampton110 Suffolk Clipperhttps://sctbus.org/portals/32/Schedules/Route%20SC%20Clipper.pdf Suffolk Clipper scheduleFarmingvilleLIE Exit 63Park & Ride→AM----←PMMelvilleHub Drive Long Island Expressway, New York State Route 110Weekday rush hour peak direction service only. Serves Islandia, Hauppauge and the NY 110 corridor. The Suffolk Clipper is also known as Route 110.

History of current routes

These current routes are replacements and reconfigurations of the previous routes that were prefixed with an "S" label, although more localized routes did not have the prefix. The prefix denoted Suffolk County, akin to route labeling in other transit systems around the region. See further down in this article for historical information about all of the former routes. Most of the routes listed in this table replaced all of the former routes on October 29, 2023.https://sctbus.org/Route-Comparison Suffolk County Transit Route Comparison Guide