On September 28th, 2012, Lewis Hamilton’s decision to leave McLaren for Mercedes in 2013 was announced, and Pérez was subsequently confirmed as Hamilton’s replacement. He also replaced Hamilton in McLaren’s cartoon Tooned. Despite being his debut season with the British team, Pérez aims to win the 2013 championship.

In the season-opening race in Australia, Pérez qualified 15th and finished in 11th position, later describing the weekend as “difficult” for himself and the team as a whole. The McLaren MP4-28 couldn’t find its balance.

Pérez started the Malaysian Grand Prix from ninth on the grid, and finished the race in the same position, scoring his first points for McLaren. Pérez also achieved the fastest lap of the race, having pitted for fresh tyres, with an average speed of 201.159 km/h.

In the Bahrain GP, he started 12th on the grid and finishing 6th ahead of Alonso (8th) and his teammate Button (10th), with whom he had a fierce duel in which they touched on a couple of occasions, increasing the competition between drivers in McLaren on the following races. The McLaren MP4-28 seemed to improve for the next European races.

In Spain, Sergio goes through the Q3 and gets the 9th position. In the race he finished in the same position. At the 2013 Monaco Grand Prix, Pérez accessed again to the Q3 in a rainy session where he achieved the 9th position for Sunday. In the race, Sergio performed several risky overtaking moves before retiring after a break problems due to a collision with Kimi Räikkönen.

Two weeks later in Canada, Checo couldn’t make it through the Q3, qualifying in 12th position. During the race, the Mexican won another racing fight with his teammate Jenson Button, finishing before him in the 11th position. The MP4-28 is not on shape to fight for the first positions.

At the German Grand Prix, the MP4-28 showed a little improvement after the disappointing race in Silverstone, where the McLarens couldn’t finish on points again, after the left rear tyre of Sergio’s car exploded when he was 5th in the race. For Nürburgring Pérez qualified in 13th because of a problem on his diffuser, but in the race after a very good start, Checo got the 9th position. At the end of the race finished 8th.

At the Indian Grand Prix, Sergio recorded a season-best fifth place, finishing four seconds shy of the podium, a result that left him “extremely satisfied”.

On November 13th, 2013, Pérez confirmed that he would be leaving McLaren at the end of the season.