Jared McCann scored for the Kraken (33-34-13), who were playing the second of a season-ending four-game road trip; they lost 3-1 at the Dallas Stars on Saturday. Joey Daccord made 24 saves.
"We just have to play for each other," McCann said. "Obviously, it's tough not [to] have a chance to play for the playoffs. That's tough. It's hard to find motivation, but we have to play for each other. We can't shy away from battles."
McCann put Seattle ahead 1-0 at 14:24 of the first period when he picked off Marco Scandella’s pass near the Kraken blue line that led to a rush up ice, and he scored with a wrist shot from the right face-off circle.
"We had good energy and we started the game well," Kraken coach Dave Hakstol said. "We gave up that late goal in the first period, and that gave them a bit of energy."
Kapanen tied it 1-1 at 18:18 with a shot from the left circle after Alexey Toropchenko checked Seattle defenseman Justin Schultz along the wall inside the defensive zone and created an odd-man rush.
"I feel like throughout the year, I probably would have pulled up and tried to make a pass or something else," Kapanen said. "So, I thought I'd try shooting it for a change and it went in."
Brayden Schenn scored his 20th of the season on a delayed penalty breakaway at 16:37 of the third, a shot from a sharp angle off the top of Daccord's skate, to make it 3-1.
Walker scored an empty-net goal at 19:00 for the 4-1 final.
"I felt we really didn't start getting ourselves going until probably around the last five minutes of the second period," Blues coach Drew Bannister said. "I thought we started to play better at that point, and that carried over into the third for us."
NOTES: St. Louis finished 25-14-2 at home. … Kyrou extended his point streak to six games (nine points; six goals, three assists). ... Blues defenseman Nick Leddy had an assist and was plus-4 in a game-high 25:08 of ice time. ... It’s the third straight season Schenn has scored 20 goals, and the eighth time in his NHL career. ... It was McCann’s 29th goal of the season, but just his second in the past 17 games.