The midfielder inked a two-and-half-year contract with the Portuguese champions in a deal that sees full-back Miguel Lopes move in the opposite direction.
With Tottenham Hotspur chasing Joao Moutinho, as revealed exclusively by Goal.com, coach Vitor Pereira did not want to leave his side short of numbers in midfield and swooped for the Russian international.
The 30-year-old said that the Dragoes’ heritage was a big factor behind him deciding to make the move from their Liga rivals, and added that he wants to help the side build on their illustrious history.
“I have spent almost six years in this country and Porto have won the title practically every year,” he told reporters.
“Everybody knows that Porto are a great team with a big, strong structure. Their results are better than those of any other Portuguese club.
“I hope to win trophies at Porto and to progress as a player and person.”
The Porto president Pinto da Costa added that he feels Izmailov will add some depth to their squad.
“Izmailov will strengthen our squad. Luckily, we have a strong team, but it's not just about 11 players. I think Marat will get a feel for our playing style and will appreciate our club spirit.”
Meanwhile, right-sided defender Lopes has made the move in the other direction, agreeing a two-year deal at Estadio Jose Alvalade.