Kuzma hit back-to-back threes in the final three minutes of a see-saw battle to finally sink the Suns, shortly after Phoenix had taken a 113-111 lead with 3min 29sec left at the Talking Stick Resort Arena, AFP reported.
A LeBron James three-pointer put the Lakers 114-113 ahead before Kuzma weighed in to stretch the lead to 120-113.
"I've been finding my rhythm all season," Kuzma said of his crucial pair of late three-pointers.
"I feel like every single game I've been getting better with my rhythm and timing.
"It kind of clicked a little bit. I know I can shoot," added Kuzma, who finished with 23 points off the bench while Anthony Davis led the Lakers with 24 points and 12 rebounds.
James added 19 points, 11 assists and seven rebounds as the Lakers made an instant return to winning ways following Sunday's loss to Toronto.
James meanwhile praised the contribution of Kuzma, saying he had never doubted the 24-year-old's ability to deliver.
"It was only a matter of time," James said.
"And it came at the right time, against a tough team. It was great to have the Kuz that we know he's capable of.
"He was very patient, took the shots that came to him ... Kuz is a huge piece of this puzzle."
The win saw the Lakers improve to 8-2 at the top of the Western Conference, continuing the franchise's resurgence under head coach Frank Vogel.
Phoenix meanwhile fell to 6-4 with the defeat. Devin Booker and Ricky Rubio led the Suns scoring with 21 points apiece.
'Whatever it takes'
Elsewhere Wednesday, Trae Young exploded for 42 points as the Atlanta Hawks upset the Denver Nuggets 125-121 in Colorado.
Young also added 11 assists in a virtuoso display that was the 21-year-old's fifth 30-point game of the season and his third in a row.
"It felt good," Young said.
"It felt even better because we won. I'm glad I was able to knock some shots down to help us win.
"I'm just trying to do whatever it takes, whether it's scoring, whether it's getting everybody involved, just trying to do whatever it takes."