The Venezuelan attacker, who has six goals in the Russian Premier League this term, has completed his move to the Petrovsky Stadium after catching the eye over the past 18 months
The Venezuela international, 24, has signed a five-year deal with his new club and has been handed the No.9 jersey.
Zenit were keen to add some more firepower to their squad ahead of the second half of the season and are hopeful Rondon can provide them with goals as they look to win the title after finishing second last term.
Rondon started his professional career with Aragua and also wore the jerseys of Las Palmas and Malaga before joining Rubin in the summer of 2012.
Zenit currently sit joint first in the Russian league table with Lokomotiv Moscow on 40 points from 19 games, while they have also qualified for the Champions League round of 16, where they meet Borussia Dortmund.