Marcin Gortat, starting in place of the injured Dwight Howard, recorded his second career double-double with career bests of 16 points and 13 rebounds as the Magic improved to 19-6, their best 25-game start since opening the 1994-95 season at 20-5. Rashard Lewis added 21 points and Courtney Lee had 16.
Andris Beidrins scored 23 points to lead the Warriors, who have lost 12 of their last 14 games. Marco Belinelli added 19 points and Jamal Crawford scored 16.
Nelson made nine of his first 11 shots in the second half after missing seven of 11 in the first half. He scored 15 points in the third quarter as Orlando continually pulled away after Golden State tied the game at 53 with 8:48 remaining.
Nelson hit four consecutive shots, three of them from long range, to help the Magic regain the advantage for good. Tony Battie, who had 12 rebounds, tipped in Nelson's only miss of the third quarter.
Gortat held his own against Biedrins, limiting the Warriors' center to nine rebounds. Gortat brought career totals of 30 points and 31 rebounds into Monday's contest.
Golden State's Stephen Jackson, trying to play through a sprained left hand, is 6-of-41 in his last three games. He was 20-of-46 in the three games before his injury.
The Magic led at halftime, 46-40.
Notes:@ Gortat brought career averages of 1.5 points and 1.9 rebounds into Monday's action. ... The Magic are 15-3 since starting the season 4-3. ... Biedrins did not record a double-double for only the second home game.