Porzingis had 16 points, hitting 5-of-6 from inside 3-point range, with six rebounds, two blocks and two assists in 23 minutes for the reigning champion Celtics in a 126-94 home rout of the Los Angeles Clippers.
"Good to go and looking forward to many, many great wins," Porzingis said.
Latvian center Porzingis had been sidelined for five months following left ankle surgery last June after being injured in the NBA Finals.
"It has been killing me inside not to be able to be out there," said Porzingis. "But it was worth the wait to come back now and finally be with my guys.
"It has been maybe a couple weeks I've been nearing the finish line of starting to play and as I was ramping up I was getting more and more antsy to be out there finally. And here it is."
Asked about his ankle, Porzingis said, "It wasn't as bad as I thought it would be. I did have a couple flat tires on some lobs but I was still able to finish it and I'm happy with the game, happy with the win and with each game I'm only going to find my rhythm more and more."
Jayson Tatum and reserve Payton Pritchard each scored 20 points to lead the Celtics while Derrick White had 19 and Jaylen Brown added 17.
"No matter who is in or out on this team, we're an unbelievably built team," Porzingis said. "It's like nothing, whoever is out, we can still win any game."
Ivica Zubac led the Clippers with 23 points and 10 rebounds while James Harden had 19 points, eight rebounds and nine assists.
At Memphis, Morant was back to his fast-breaking, slam-dunking top form to spark the Grizzlies over Portland 123-98.
Morant scored 20 of his 22 points in the first half and added 11 assists while Jaren Jackson Jr. had 21 points for Memphis.
Morant has missed the past eight games for the Grizzlies after suffering a hip injury in a fall against the Los Angeles Lakers on November 6.
In Atlanta, Irving scored 22 of his 32 points in the second half to lead the Dallas Mavericks over the host Hawks 129-119.
Jaden Hardy added 23 points while Naji Marshall and Spencer Dinwiddie each added 22 for the Mavs. Jalen Johnson scored 28 to lead Atlanta, which has lost three in a row.
Ivey wins for Detroit
Detroit's Jaden Ivey scored the last of his team-high 25 points on a floater at the final buzzer to give the Pistons a 102-100 victory over visiting Toronto.
Tyrese Haliburton scored 34 points and passed off 13 assists to lead the host Indiana Pacers over New Orleans 114-110.
Germany's Franz Wagner scored 21 points to lead the Orlando Magic to a 95-84 victory at Charlotte despite LaMelo Ball's game-high 44 points for the Hornets.
