The Maine Celtics are back in the playoffs. And their home fans will get to welcome them back.

Mfiondu Kabengele scored 29 points and grabbed 16 rebounds in another eye-catching performance, Denzel Valentine added 20 points, and the Celtics clinched their first NBA G League playoff berth since 2017 with a 110-97 victory over the Westchester Knicks in the regular-season finale in front of a sold-out crowd of 2,417 at the Portland Expo Thursday.

“It’s always exciting. Anyone who’s a competitor wants a chance to play for a championship, it doesn’t really matter what level you’re at,” said Celtics Coach Alex Barlow, who also got 17 points each from JD Davison and Luka Samanic. “We get a chance to do that. … That’s a really good feeling, a really exciting feeling.”

The victory also clinched a top-four seed in the Eastern Conference, and the home playoff game that comes with it. Six teams in each conference qualify, the top two seeds get byes, and the teams play single-elimination rounds in the conference playoffs. The Eastern and Western champions will meet for a best-of-three final.

“This is what we wanted,” Valentine said. “We’ve got one of the best fanbases in the G League.”

The performance that punched the ticket began with an uninspiring start. Maine and Westchester went into halftime tied at 49, and the Celtics had turned the ball over 10 times.

“We weren’t good in the first half. There’s no way around it,” Barlow said. “We did not play well, we did not play hard enough.”

Barlow wrote four keys for the team on the marker board in the locker room at the break. The fourth read “Effort.” After the game, it was still up.

“When Coach calls out that, there’s nothing you can say,” Kabengele said. “It’s all about accountability, effort on all parts.”

With Kabengele, one of the team’s two-way players, leading the way, the Celtics rolled in the third. Kabengele scored 12 points in the quarter alone, including a breakaway dunk that made it 71-63 and ignited the Expo crowd.

The game was Kabengele’s seventh straight with a double-double. He has 33 rebounds over his last two games.

“He’s a monster, man,” Valentine said. “He belongs in the NBA. … I think he’s a winner, too, as well. He won the (league) championship last year (at Rio Grande Valley). Whenever something’s on the line, he always makes big plays.”

Kabengele said he’s been following the wishes of General Manager Jarell Christian, who sent the former first-round pick a text urging him to step up.

“I just took that upon myself,” he said. “Put more energy towards my effort. Close out a little harder. When I box out, put more contact. When I set screens, really set it, and roll fast.”

The team followed his lead. The 3-point happy Celtics, who entered the night with the second-most attempts in the league, shot only 29 percent from deep, but defense and transition allowed them to pull away Thursday. The lead swelled to 16 before the end of the quarter, and Westchester never got closer than eight points in the fourth.

“The guys did a really good job not settling. Like ‘Hey, it’s not working for us tonight, we’ve got to find other ways to score,’ ” Barlow said. “The big emphasis (was), when we got stops and rebounds, run. Run, run, run. Try to get layups in transition. … I thought they did a really good job pushing the pace.”

And now, with a home playoff game up next, the Celtics can rest. For a little while.

“I’m happy that we finished the season out strong,” Kabengele said. “But going forward, my only concern is guys getting too comfortable. I feel like a lot of guys got excited because we got home court, it’s like ‘Home court’s going to save us?’ … I want to make sure guys are locked in.”