Kareem Abdul-Jabbar scored 26 points and Magic Johnson had 24 points and 10 assists to lead Los Angeles in Phoenix.
The victory was the Lakers' eighth straight and their 10th in 11 games, raising their record to 50-18. Phoenix, which dropped its fourth straight, is 31-38.
The Lakers moved in front early, leading by nine points midway through the first quarter and increasing the lead to 11 just before halftime.
However, the Suns made their first six shots of the second half to take a 73-70 lead on a 16-foot jumper by rookie Jay Humphries with 9:52 left in the quarter.
The Lakers then went on a 13-0 run, regaining the lead and pushing it to 83-73 on a free throw by Larry Spriggs with 5:40 to go in the third quarter.
The closest the Suns could get after that was five points late in the third quarter. The Lakers' final margin was their largest of the game.
Byron Scott had 21 points for Los Angeles and James Worthy and Michael Cooper had 12 each. Phoenix got 19 points from Alvan Adams and 17 points and 12 rebounds from Maurice Lucas.