The 1969–70 St. Louis Blues season involved finishing in first place in the West Division for the second consecutive season. The Blues were the only team in the West Division with a winning record as they finished 22 points ahead of the second place Pittsburgh Penguins. The Blues matched their previous season's total of 37 wins but finished with 86 points, two points shy of the previous season's points total. NHL legend Camille Henry played his final game with the St. Louis Blues. Henry got 3 points in 4 games.
From a goaltending standpoint, the franchise experienced many changes. Glenn Hall had retired at the end of the 1968–69 season but returned. Despite an appearance in the All-Star Game, Jacques Plante played his final season in St. Louis. He was sold by the Blues to the Toronto Maple Leafs for cash, May 18, 1970. Ernie Wakely was acquired from the defending Stanley Cup champion Montreal Canadiens and became the Blues starting goaltender for the following season.
In the playoffs, St. Louis defeated the Minnesota North Stars 4–2 and the Pittsburgh Penguins 4–2 to advance to their third consecutive Stanley Cup Final, where they were swept by the Boston Bruins. Phil Goyette became the first Lady Byng Trophy winner in franchise history as he led the team with 78 points.
As he did with the Chicago Black Hawks in 1966, Hall retired from St. Louis at the end of the 1968–69 season. He was talked into returning, usually with a promise of more money, but he didn't profess to enjoy his livelihood. Although Hall stayed in St. Louis, he still got nauseous before each game as he did earlier in his career.
Ernie Wakely played 2 games from the Montreal Canadiens from 1962 to 1969. On June 27, 1969, Wakely got his big break when the Canadiens dealt the 28 year old to the St. Louis Blues for Norm Beaudin and Bobby Schmautz. The 1969–70 season was a career season for Wakely. He appeared in 30 games for St. Louis, registering a 2.11 GAA and four shutouts.
Wakely had to take over from the legendary Glenn Hall. Wakely made the most of his opportunity as he helped lead the Blues to the Stanley Cup finals. The Blues were defeated in four straight games by Bobby Orr's Boston Bruins.
In the West Division playoffs, the St.Louis Blues ousted the Minnesota North Stars in six games. The Blues won the first two games at the St. Louis Arena. Game three at the Metropolitan Sports Center featured Gump Worsley's sharp goaltending and Bill Goldsworthy scoring two goals in a 4–2 win for the North Stars. Cesare Maniago played in goal for Minnesota in game four and picked up a 4–0 shutout, tying the series. Game five at St. Louis Arena was tied 3–3 when St Louis scored three goals in the third period by Red Berenson, Terry Gray and Jim Roberts and the Blues won 6–3. In game six, Ab McDonald scored two goals as the Blues eliminated the North Stars by a score of 4–2.
For the third consecutive year, the Blues were swept in the Stanley Cup finals. This time, they faced the Boston Bruins, who, with stars like Bobby Orr and Phil Esposito, were more than a match for them. The first three games were not close. The Blues managed to force overtime in game 4, but Orr scored the most famous goal in NHL history to end the series.