Thompson scored 23 points to lead the Seattle Storm to a 73-66 win against the Los Angeles Sparks on Thursday.
Selected to a record ninth All-Star game as a replacement for the injured Brittney Griner, she also had a team-high eight rebounds and Tanisha Wright added 15 points as the Storm (7-10) snapped a seven-game losing streak to Los Angeles.
Thompson, who is retiring after this season, downplayed her final regular-season appearance here but acknowledged the pre-game ceremony honoring her.
"I totally appreciate it," said Thompson, who grew up in L.A. and played at USC and for the Sparks from 2009-11.
"This is my hometown. This is where I grew up. All my family and friends are here. ... I appreciated that and having the opportunity and (Sparks general manager) Penny (Toler) giving me the opportunity to come home and play here. It means a lot. It was a key part of my career."
Candace Parker had 24 points and 10 rebounds for the Sparks (12-6), who have lost two straight at home after a 19-game regular-season home winning streak, the second-longest in league history.
The Sparks, who lead the WNBA in field-goal percentage, shot a season-low 31 percent.
Parker said there was a lack of urgency in the final game before the All-Star break.
"I think we were very lax," Parker said. "We just played like we knew we were going to come back like we did (last Saturday) in Seattle, and they came mad that we took it from them in Seattle. There's not much difference between this game and the last game.
"We have to figure out, through this break, I hope, that we're not always going to be able hit those shots and teams are going to make adjustments on us and we have to do the same."
Thompson scored five straight points, on a left-handed hook and a three-point play, to give Seattle a 63-51 lead. She was fouled on a rebound and made the ensuing free throws to make it 66-61.
Camille Little scored on a left-handed shot in the paint and Thompson rebounded a Sparks miss after a timeout to effectively seal the win.
"She'll not admit this," Seattle coach Brian Agler said of Thompson. "She really likes our team but there was one reason she came to Seattle, and that was to have a chance to make a run at something with Sue (Bird) and Lauren (Jackson) and unfortunately that hasn't worked out.
"But she's sort of got a rejuvenated energy now sort of being the leader in a lot of ways on our team. She came back in a lot better shape this year than she was a year ago. I was happy. Inside, I think she was looking forward to coming back and playing one last time."
Thompson and Wright each scored 11 points to lead Seattle to a 41-27 edge at halftime -- the lowest-scoring first half by L.A. this season.
Thompson made three 3-pointers in the first 5:04 and scored 11 of Seattle's first 17 points. Seattle had a 16-1 advantage in rebounds early in the second quarter and 23-7 at the half.
L.A. went on a 19-6 run in the third quarter capped by Jenna O'Hea's 3-pointer that closed the deficit to 47-46. But Seattle scored six of the next eight points to finish the quarter.
Second-leading scorer Kristi Toliver was 4 for 9 from the field, which included a 3-pointer at the buzzer.
"They played her hard," Sparks coach Carol Ross said. "She's been a thorn in their side for most of her career. But for Toliver, it's been a pretty tough row. Part of it is she's a little banged up. At the same time, you have to give Seattle credit, they've done a great job guarding her."
The Sparks lost consecutive regular season home games for the first time since Aug. 3-7, 2011.
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