Lakers guard Kobe Bryant, the defending NBA scoring champ, did not play. Bryant has yet to play in the exhibition season after undergoing knee surgery in July. The Lakers have one exhibition game remaining before opening the season at home against the Suns on Oct. 31.
Walton keyed a 9-2 run late in the fourth quarter that gave Los Angeles (4-3) a 93-89 lead. His 3-pointer with 41 seconds left capped the run.
After Leandro Barbosa scored for Phoenix (4-3) on a reverse layup with 31 seconds remaining to cut the lead to 93-91, Walton rebounded a miss by Sasha Vujacic. The Suns were forced to foul and Walton hit one of two free throws for the final score.
With a chance to tie the game, Jumaine Jones missed a 3-pointer from the top of the key with three seconds left.
Lamar Odom had 18 points and nine rebounds for the Lakers. Center Andrew Bynum added 16 points and nine boards.
Barbosa led Phoenix with 19 points and reserve Marcus Banks added 15. Two-time MVP Steve Nash finished with 10 points and 11 assists in 26 minutes.
Los Angeles had seven players unavailable due to injury, including centers Chris Mihm (ankle surgery) and Kwame Brown (bruised rotator cuff and bursitis).
The Lakers were also without coach Phil Jackson, who underwent replacement hip surgery on Oct. 3. Jackson is expected to be coaching by the season opener.