BOSTON — This was looking to be a green fairytale night for Kemba Walker, finally playing again and doing so against the team that unceremoniously shipped him out last June.

And perhaps to coach Tom Thibodeau’s shock, Walker was leading the way to a Knicks’ victory by scoring 29 points through three quarters with the Knicks leading by two.

But in the end, there was just another defeat, with Walker fouling out with 2:06 left after failing to score in the final period as the Celtics rolled to a 114-107 victory Saturday at TD Garden.

“I played all right, pretty good I think,’’ Walker said. “We fell short and couldn’t come out with the win — which is the most important thing.’’

“I know I should be playing, so no question, it feels great. But whatever situation I’m in, I’m gonna stay locked in.’’

Walker also waffled about his future. When asked how he’s handled the past few weeks, in which he hasn’t played since Nov. 26 (nine straight games, all coach’s decision), Walker said, “I hate it. I want to play. Guys went down. I got to fill in. Do what I can until they get back.’’

Thibodeau didn’t fully shut down the notion Walker might have improved his standing in the future. But just the same, it still could be his last game as a Knick if Derrick Rose comes back Tuesday.

“He played really well,” Thibodeau said of Walker. “Really well. That’s what he’s supposed to do. He’s a pro, great character and played well.”

Walker sounded as if he thinks he’s still destined for the end of the bench soon enough. Walker started at point guard because of the six COVID-19 positives and an ankle injury to Derrick Rose.

Walker finished with 29 points, making 8 of 20 shots and hitting 5 of 11 3-pointers. He also made 8 of 10 free throws.

When asked if he still wants to be in his native New York, Walker said, “I want to play. I don’t know. I don’t know what the future holds. I do feel like I have a lot to give still. That’s up to these guys.’’

Walker also sounded perplexed at being told to foul intentionally in the backcourt late in the game. It was his sixth. “I was told to foul. I’m not gonna lie,’’ Walker said. “I didn’t know I had five. But I heard them on the sideline, they told me to foul. Very, very unfortunate situation, but that’s what I was told to do.’’.

During pregame intros, Walker received a warm ovation from the Boston crowd as the scoreboard read: “Welcome Back, Kemba.’’

“It felt great,’’ Walker said. “There was a lot of love from the fans, which I really, really appreciated.’’

Former Celtic, Evan Fournier, also produced with 32 points but it wasn’t enough to offset the COVID Boston Big 3 of Jayson Tatum (25), Jaylen Brown (23) and Josh Richardson, who racked up 27 points. “[Richardson] had a monster game,’’ Thibodeau said.

For three quarters, Walker was proving size doesn’t matter. Thibodeau had canceled Walker, with the lone explanation being he wanted more size at that position. Walker scored 18 points in the third quarter as the Knicks took a six-point lead.

Fournier, who played with Walker in Boston, said what Walker did after his hiatus was remarkable.

“It’s tough what he did,’’ Fournier said. “When you’re watching, you don’t really how much an impact it has on you sitting so long with rhythm and confidence. We all know his résumé.

“It was good to see Kemba smiling again.’’

Walker said he has had no conversations with Thibodeau since he got his demotion. Instead, Walker went out of his way to cite assistant Johnny Bryant.

“Me and my guy Johnny Bryant, we’ve just been in the gym continuously working, trying to stay ready,’’ Walker said. “I appreciate him putting the time in with me, keeping me prepared. Big shoutout to him.’’

Thibodeau, for his part, wouldn’t nix the possibility of Walker getting back into the mix. “We’ll see, we’ll see,’’ Thibodeau said. “We have to look at everything in totality,’’

“I have no idea, brother man,’’ Walker said about getting back in the rotation. “That’s not a question for me. I just have to continue to stay ready. I have no idea what the future holds.’’

This could have been a victory if Julius Randle played to his All-Star potential. He was ineffective despite his 20 points and nine rebounds. He was just 6-of-19 from the field.

And the Knicks got just three points from their depleted bench — all from Mitchell Robinson — in Thibodeau’s eight-man rotation. The Knicks fell to 13-17 while the Celtics moved to .500 at 15-15.

Each team had six players in COVID-19 protocols. The Celtics were missing eight players total.

“Hard-fought game,’’ Thibodeau said. “Got to find a way at the end.’’