Toronto scored the first three goals inside 36 minutes, before Zlatan's cracker inspired a Galaxy comeback.
With LA Galaxy 3-0 down just before half-time, the Swedish forward struck with a spinning backheel volley.
Ibrahimovic's first goal for the Galaxy was a 40 yard wonder strike that made the score 3-3 in the Los Angeles derby, following that up with a 90th minute victor in his debut match.
Ibrahimovic's goal not only took his career goals tally to 500, it also inspired his side to take the match to level terms with a 3-3 scoreline in the middle of the second half.
It is a goal glut that started at Malmo and has continued with Ajax, Juventus, Inter Milan, Barcelona, AC Milan, PSG and Manchester United. "Obviously it's not good to lose ... but I'm happy for Toronto because they'll be remembered as my 500th victim", he was quoted as saying to TSN after the match.
At worldwide level for Sweden, he made 114 senior appearance and scored 62 goals.
Speaking after the clash, he said: "I was close to the goal". 'I have more goals than he has games.
The 36-year-old Swede joined Lionel Messi and Cristiano Ronaldo as the only active players with 500 goals for club and worldwide play, cutting the Galaxy's lead to 3-1 in the 43rd minute. "It came from a cross and I turned around and I hit it".