The 2017–18 St. Louis Blues season was the 51st season for the National Hockey League (NHL) franchise that was established on June 5, 1967. The Blues missed the playoffs for the first time since the 2010–11 season.

Off-season The Blues made a decision to change the goalie coach on May 9, 2017, allowing Martin Brodeur to concentrate on his front office duties. Brodeur will lead the search for a new goalie coach.

All the other assistant coaches were let go on May 16. The team's president of hockey operations and general manager Doug Armstrong announced that Ray Bennett, Steve Thomas, Rick Wilson and Ty Conklin will not return to the Blues' coaching staff next season.

Armstrong announced on May 16 that the Blues had ended their minor league affiliation with the Chicago Wolves of the American Hockey League (AHL). The Wolves then became the first affiliate of the NHL expansion team, the Vegas Golden Knights. With 31 teams in the NHL and 30 teams in the AHL, the Blues would partner with the Golden Knights and continue sending prospects to the Wolves while also looking into having their own affiliate for the 2018–19 season. They would eventually affiliate with the Tulsa Oilers of the ECHL in August.

Armstrong announced on May 24, that Darryl Sydor, has been named assistant coach, signing a three-year contract. He spent last season as an assistant with AHL's Chicago Wolves, helping the club finish first in the Central Division in the regular season and reach the second round of the 2017 Calder Cup playoffs. Prior to that one season, he served as an assistant on Blues head coach Mike Yeo's staff during his five-season stint with the Minnesota Wild. Before beginning his coaching career, Sydor, the seventh overall draft pick to the Los Angeles Kings in 1990, appeared in 1,291 NHL regular season games across 18 seasons. The Edmonton, Alberta native played his final NHL season in St. Louis in 2009–10.

On May 25, Armstrong announced that former Blues' player Steve Ott, was signed for three years as an assistant coach.

On June 2, Armstrong announced that recently retired Blues' defenseman Barret Jackman, signed as their new development coach. Jackman said that as the team's development coach, he would primarily be working with prospects and draft picks, whether they are playing at the college, junior or AHL level. He was drafted by the Blues in the first round (17th overall) in 1999, ranks second on the club's all-time games played list with 803 games, trailing only Bernie Federko with 927.

On June 15, Armstrong finished his coaching changes, hiring Craig Berube as associate coach, Daniel Tkaczuk as an assistant and skills coach, and David Alexander as the team's goalie coach. Berube was behind the Philadelphia Flyers' bench for two seasons as its head coach (2013-2015), after spending parts of seven as an assistant. He also played 1,054 games in the NHL with the Flyers, Washington Capitals, Calgary Flames, Toronto Maple Leafs and the New York Islanders. He took over the Blues' AHL affiliate last season. In one year, he led the Chicago Wolves to a record of 44–19–13 for 101 points, a 27-point improvement over 2015–16. Tkaczuk was the sixth overall pick of the Calgary Flames in 1997, but the center played just 19 games in the NHL. His professional career ended in 2011, and he began coaching in the Ontario Hockey League (OHL) beginning in 2012. All three coaches were popular with the minor-league players in Chicago last season, particularly Berube. Alexander's hiring was welcome news to Allen, as both are natives of New Brunswick, and met when the Blues' goalie was just 14.

The Blues lost David Perron (LW) in the expansion draft for the new Vegas Golden Knights team on June 21. An established team could only lose one unprotected player during the draft to an expansion team. The Blues released their list of seven forwards, three defensemen, and one goalie, but Perron was not protected. All first and second-year professional players were exempt from the expansion draft, so players such as Robby Fabbri and Colton Parayko, who just completed their second seasons, did not have to be protected and did not count towards the Blues' protected list.

Patrik Berglund (C) had successful shoulder surgery on June 27, to repair his left shoulder he dislocated during a training session in Sweden. He is expected to be out until sometime in December. Berglund's surgery was performed by the Blues orthopedic surgeons Dr. Rick Wright, Dr. Matt Matava and Dr. Matthew Smith at the Washington University Orthopedic Center. Last season, Berglund posted a career high in goals (23) and finished with 34 points in 82 games played. For his career, the 29-year-old Västerås, Sweden native has played in 637 regular season games, scoring 151 goals and 145 assists (296 points).

Zach Sanford (LW), dislocated his left shoulder on the first day of training camp, September 16, and will miss at least five months. Jay Bouwmeester (D) suffered a left ankle fracture after a puck hit him, and will be re-evaluated in three weeks.

On September 28, the Blues announced that Robby Fabbri (C), 21, will be lost for the season after re-injuring his repaired left knee during training camp. He originally tore his ACL on February 4. He is expected to make a full recovery and is projected to participate in training camp when it begins next September, but he has been ruled out to play at any point this season or postseason. He had surgery on the knee on November 7. Dr. Bernard Bach first performed surgery on Fabbri's knee on Feb. 28 in Chicago, and he was cleared to play on July 31. Fabbri then re-injured his knee during training camp before undergoing today's operation. Fabbri has appeared in 123 career regular season games with the Blues, recording 66 points (29 goals, 37 assists) and 52 penalty minutes.

Regular season

October The Blues announced on October 10, they signed a five-year affiliation agreement with the San Antonio Rampage of the AHL to start with the 2018–19 season. For the 2017–18 season, as the Blues had no official AHL affiliation, agreed to send players to both their former AHL affiliate, the Chicago Wolves, and to the Rampage, which was still the primary AHL affiliate of the Colorado Avalanche.

For only the second time in their 51-year history, the Blues won their first four games of the season on October 10. They previously did it in the 2013-14 season, losing in their fifth game. Carter Hutton, in his first start of the season, made 32 saves on 33 shots, with the team winning 3-1.

Alexander Steen (LW) returned to active duty from his fractured hand on October 18, to help beat the Chicago Blackhawks 5-2 at home. He missed six games, and six of the seven pre-season games. Wade Megan (C) was placed on waivers. Jaden Schwartz (LW) scored a hat trick, including the third, an empty-netter 51 seconds remaining in the game. It was his third career hat trick, and the first for a Blues' player against the Blackhawks since Pierre Turgeon did it in 1998.

Before the October 27 game, after playing 10, the Blues rank third in the league in a "funny stat" with 165 blocked shots. Joel Edmundson (D) ranks second in the NHL with 33, and defense pair Carl Gunnarsson is 14th with 23. The pair are one of four teammate pairs in the top-15.

November The Blues beat the Toronto Maple Leafs at home on November 4, (6-4) seen across Canada on Hockey Night in Canada. Brayden Schenn made a career high of four assists. Team scoring leader Jaden Schwartz had three assists, and defenseman-captain Alex Pietrangelo scored two goals.

Arianna "Ari" Dougan, 11, died from neuroblastoma cancer on the morning of November 11, after an eight-year fight. She had a large influence on the Blues. She had a special bond with Vladimir Tarasenko, who invited her on a road trip with the team the past March. The trip came together after she met Tarasenko in 2015, at the team's Hockey Fights Cancer night. Tarasenko invited her to celebrate her birthday with the team. He visited her in the hospital three days before her suffering ended. The "Blues had a pregame moment of silence for Ari Dougan; it may have been the longest and quietist moment of silence I've seen" tweeted reporter Tom Timmermann that Saturday night. Use #SpreadArisLight and #FightLikeAri, if you share a story or memory about her on social media. Ari's family will drop the puck before the Hockey Fights Cancer Game against the Los Angeles Kings on December 1. Ari's friend Vladimir Tarasenko will take the faceoff. Fans in attendance are encouraged to use their cell phone's flashlight feature during the puck drop to help #SpreadArisLight ahead of the game. Fans can help raise money to fight cancer by purchasing autographed mystery pucks or special edition lapel pins outside Section 114 at the game. Fans can also download an "I Fight For" sign at stlouisblues.com/HFC to display on their social media accounts.

Jay Bouwmeester (D) returned to play on November 21, after missing the first 21 games due to a fractured ankle suffered from a puck, on the third day of training camp, September 17.

Alex Pietrangelo (D), and captain, was named on November 21, the early favorite for the Norris Trophy, as the best defenseman in the NHL from a panel of 18 NHL staff members after the first quarter of the season. After 21 games, he has scored seven goals and 12 assists (19 points), with a +9 rating. He received 73 points in the voting including nine first-place votes. He was the only player to appear on all 18 ballots. Erik Karlsson of the Ottawa Senators ranked second with six first-place votes (61 points). The trophy is awarded at the NHL Awards ceremony in June.

Patrik Berglund (C), was activated before the November 29 game, after missing the first 24 games due to a shoulder injury suffered while training in Sweden. He had surgery in June. In the 2015-16 season, he had surgery on the other shoulder, missing the first three months of the season. To make room to activate Berglund from injured reserve, the Blues have placed defenseman Nate Prosser on waivers. Despite long-term injuries to several key players, the Blues have managed to record a 17-6-1 record (35 points) through the season's first 24 games, which is good for the best record in the League. Berglund (shoulder), Robby Fabbri (knee), Zach Sanford (shoulder), and Jay Bouwmeester (ankle) have all missed significant time with injuries.

The team ended a so-so month of November, 7-5-0 (14 points; HOME: 4-4-0, ROAD: 3-1-0) scoring 42 goals, giving up 36, and kept their hold in first place by a narrow margin in both the Central Division and the Western Conference over the Winnipeg Jets (34 points), and Nashville Predators (33 points) after 25 games. The Blues earned a total of 35 points, 17-7-1 (HOME: 9-4-0, ROAD: 8-3-1), scoring a total of 86 goals, giving up 66 goals, with the 86 scoring goals leading the Western Conference. The 35 points was second in the NHL to the Tampa Bay Lightning with 36 points (17-6-2) after the same 25 games. The Toronto Maple Leafs also had 35 points but they played 27 games (17-9-1).

December The Blues will wear bedazzled jerseys during warm-ups before the December 1, Hockey Fights Cancer game, to honor Arianna "Ari" Dougan, who died on November 11, at the age of 11, after battling neuroblastoma for eight years. Her family will drop the puck prior to Friday's game as Vladimir Tarasenko takes the faceoff. The bedazzled jerseys will be autographed and auctioned online at Blues.gesture.com beginning Friday. Fans can also text "BLUES" to 52182 to bid. The auction ends December 4, and proceeds will benefit cancer research organizations.