Pavon, who made four appearances at last year's World Cup, completed his switch to the Galaxy before Wednesday's MLS deadline, with the transfer confirmed the following day.
The 23-year-old's temporary deal through to the end of the 2019 season will be covered by targeted allocation money.
The Galaxy then reportedly have the option to extend Pavon's deal for another season, at which point the club would need to free up a Designated Player slot - their three are occupied by Zlatan Ibrahimovic, Jonathan dos Santos and Romain Alessandrini.
LA were forced to cut Giovani dos Santos from their squad this season - he subsequently joined Club America - after Ibrahimovic agreed an improved contract.
It is said the Galaxy could sign Pavon to a permanent deal at the end of the 2020 campaign, with an MLS record $20million fee agreed.
Pavon had been linked with a move to the Premier League with Arsenal earlier this year.
The Galaxy's rivals and runaway Supporters' Shield frontrunners Los Angeles FC boosted their own attack with Brian Rodriguez arriving from Penarol as a Young Designated Player.
LAFC sent United States international Christian Ramirez to Houston Dynamo, while Real Salt Lake signed Kelyn Rowe, and New York Red Bulls brought in Southampton's Josh Sims until the end of the season as a Young Designated Player.