The 38-year-old Thompson capped her 17th regular season with 22 points and eight rebounds in an 85-73 win over the Tulsa Shock.
Thompson made 7 of 17 shots from the field on a night the Storm (17-17) were in control all the way. Seattle never trailed and held a double-digit lead for all of the final 24:09.
Thompson's final basket, her fourth 3-pointer of the game, gave Seattle an 85-65 lead with 1:55 remaining. She checked out of the game to a standing ovation 29 seconds later, then the game was held up for a couple of minutes after Storm coach Brian Agler coerced her to go back onto the floor to give the fans a wave.
"I told her, 'We're not in a hurry,'" Agler said after the game. "She didn't really want to do it. That's just the way she is. She's all business."
Camille Little added 14 points and six rebounds for the Storm, while Alysha Clark had 11 points off the bench. Seattle is the No. 4 seed in the Western Conference and faces No. 1 seed Minnesota in the first round.
Jennifer Lacy came off the bench to lead Tulsa with 21 points. The Shock had 15 turnovers and were 24 of 65 from the field while making all 19 of their free throws.
Thompson is the WNBA's leading scorer (7,488), ranks second in rebounds (3,070) and is an eight-time All-Star. During the 2013 season, she averaged 14.1 points and 5.8 rebounds per game and had a career-high 60 3-pointers for an injury-plagued Seattle team that made a surprising playoff run without injured stars Lauren Jackson and Sue Bird.
The night was dedicated to Thompson throughout, with video messages from legends like Sheryl Swoopes, Cynthia Cooper, Teresa Weatherspoon and Jackson (currently sitting out the season at home in Australia) showing on the scoreboard during stoppages in play. There was also a postgame celebration that had been months in the making, from about the time Thompson announced her retirement in May.
"It's a great feeling knowing people appreciate your body of work," Thompson said after a postgame ceremony. "I'm glad it's over. Now we're not waiting for it, and we can just concentrate on the next game."
Thompson said she has no second thoughts about her decision, despite a productive final season.
"I want to go 12 more games," she said, referring to the postseason. "Anything beyond that, no.
". I'd rather retire from the game than have the game retire me."
She came out of the gates fast on a night when it was apparent that she would be the primary scoring option.
Thompson hit 3-pointers on the Storm's first two possessions of the game, then Seattle used a 9-0 run a few minutes later to run out to a 21-10 lead through the first quarter.
Thompson cooled off after her hot start, but the Storm kept the foot on the gas to lead 44-28 at the half. Thompson had a team-high 11 points despite 3-of-9 shooting from the field in the first half, while Tiana Hawkins provided a boost off the bench by scoring the Storm's final seven points of the half.
A 10-2 spurt by Seattle to open the second half pretty much put the game out of reach, especially on a night when the Shock (11-23) had nothing on the line.
It marked the second time in three nights that the Storm beat Tulsa after losing the first three meetings of the season to the Shock.
During the 30-minute ceremony that followed the game, Thompson held the hand of her 7-year-old son, Dyllan, while thanking each of her teammates personally. WNBA President Laurel Richie, chief of basketball operations Renee Brown and former Houston Comets teammate Cynthia Cooper were among the people to address Thompson during the ceremony.
"You will always be a part of our family," Brown told Thompson, who was the No. 1 overall pick in the league's inaugural draft in 1997. "You set the example for all professional athletes."
Thompson finished off the ceremony by saying: "It has been my pleasure, and it has been my absolute blessing."
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