Young had been on the disabled list since June 26 with a sprained ankle, while Plouffe was sent down to Triple-A on June 2 after struggling badly at shortstop. Both returned on Thursday night to get the Minnesota Twins off to a good start in a critical home stand.
Plouffe hit a big two-run homer and Young had three hits to lead the Twins to an 8-4 victory over the Kansas City Royals.
"That's the mentality I have now, just help the team anyway I can," said Plouffe, who tore up the minor leagues with 15 home runs in 51 games. "I don't know where I'm going to be playing, but it doesn't matter. When I get in there, have good at-bats and play sound defense."
Melky Cabrera had two hits, an RBI and threw a runner out at home from center field for the Royals, who watched their bullpen let a close game get out of hand.
Chen gave up four runs on nine hits with three walks in five innings for the Royals.
"Just a day, actually the first day all year where nobody was sharp," Royals manager Ned Yost said.
The Twins went 24-11 in the final 35 games before the All-Star break, shaving 10 games off their deficit in the AL Central and started the night trailing Detroit by 6½ games. It marked the start of a crucial stretch of 12 home games in a row, all against division foes.
"It's a big mountain we put ourselves at the bottom of and we're still working our way back up," Twins manager Ron Gardenhire said.
The Royals were showing some promise of finally digging out of the cellar early in the season, starting the year 20-17. They are 17-38 since then to fade out of contention, though youngsters like Eric Hosmer and Mike Moustakas are giving their long-suffering fans reason to hope that better days are around the corner.
It was ugly early for the Twins, who committed two errors in the first inning. Cabrera scored on a wild pitch and Alex Gordon hustled home from second base on the play after Mauer's ill-advised pitch to Liriano at home plate skipped by him.
With a fastball that never topped 84 mph, Chen was somehow able to get through four scoreless innings. He stranded seven runners before the Twins finally got to him in the fifth.
Young hit his second double of the game to score Valencia and Plouffe's two-run homer hit high off the foul pole in left field to give the Twins a 4-3 lead.
"After the Babe Ruth-like performance he put on when I was in Rochester with him, it was good to see him first game up here go deep," Young said.
Plouffe, who was recalled from Triple-A to start this game, was initially slated to play first base. But Jim Thome was a late scratch with a left toe injury, so Plouffe was moved to DH.
Wood came out to start the seventh and walked Ben Revere with the bases loaded before hitting Casilla to make it 6-3. Mauer followed with a two-run single of Everett Teaford to cap the four-run inning.
Notes: The Twins said they were awaiting clearance from MLB before starting CF Denard Span (concussion) on a rehab assignment. OF Jason Kubel (sprained foot) and RHP Kevin Slowey (abdominal strain) also are getting closer to returning. 1B Justin Morneau (neck surgery) has started to work out and could start swinging a bat in another week or so if all goes well. ... Chen faced Casilla three times, allowing two singles. He threw over to first base to keep the speedy Casilla close to the bag 14 times total. ... Mauer's error snapped a career-high 96-game errorless streak.