On 28 September 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.
This also ended Pérez' association with Ferrari, as he was released from its driver academy.

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.
He started the Malaysian Grand Prix from ninth on the grid, and finished the race in the same position, scoring his first points for McLaren.
He also achieved the fastest lap of the race, having pitted for fresh tyres.

In the Bahrain GP, he started 12th on the grid and finishing 6th ahead of Ferrari's Fernando Alonso (8th) and his teammate Jenson 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.

After the Bahrain Grand Prix, Jenson Button said of Pérez's driving style:
I've raced with many team-mates over the years and with quite an aggressive team-mate in Lewis, but I'm not used to driving down the straight and then my team-mate coming along and wiggling his wheels at me and banging wheels with me at 300km/h.
I've had some tough fights in F1 but not quite as dirty as that.

That's something you do in karting and normally you grow out of it but that's obviously not the case with Checo [Pérez].
Soon something serious will happen so he has to calm down.
He's extremely quick and he did a great job today but some of it is unnecessary and an issue when you are doing those speeds.

— Jenson Button speaking to ESPN about Pérez after the 2013 Bahrain Grand Prix
At the 2013 Monaco Grand Prix Pérez performed several aggressive overtaking moves, before retiring after colliding with Kimi Räikkönen.
Following the incident Räikkönen said that Pérez should be "punched in the face".
Pérez recorded a season-best fifth-place finish in India, finishing four seconds shy of the podium, a result that left him "extremely satisfied".

Pérez confirmed on 13 November 2013 that he would be leaving McLaren at the end of the season to be replaced by Kevin Magnussen.
On 12 December 2013 (exactly a month after it was announced he would leave McLaren), Force India confirmed that Pérez would join Nico Hülkenberg in their driver line-up for 2014 in a 15 million Euro deal.
On 28 September 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. This also ended Pérez' association with Ferrari, as he was released from its driver academy.
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. He started the Malaysian Grand Prix from ninth on the grid, and finished the race in the same position, scoring his first points for McLaren. He also achieved the fastest lap of the race, having pitted for fresh tyres.
In the Bahrain GP, he started 12th on the grid and finishing 6th ahead of Ferrari's Fernando Alonso (8th) and his teammate Jenson 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.
After the Bahrain Grand Prix, Jenson Button said of Pérez's driving style:
I've raced with many team-mates over the years and with quite an aggressive team-mate in Lewis, but I'm not used to driving down the straight and then my team-mate coming along and wiggling his wheels at me and banging wheels with me at 300km/h. I've had some tough fights in F1 but not quite as dirty as that.
That's something you do in karting and normally you grow out of it but that's obviously not the case with Checo [Pérez]. Soon something serious will happen so he has to calm down. He's extremely quick and he did a great job today but some of it is unnecessary and an issue when you are doing those speeds.
— Jenson Button speaking to ESPN about Pérez after the 2013 Bahrain Grand Prix
At the 2013 Monaco Grand Prix Pérez performed several aggressive overtaking moves, before retiring after colliding with Kimi Räikkönen. Following the incident Räikkönen said that Pérez should be "punched in the face". Pérez recorded a season-best fifth-place finish in India, finishing four seconds shy of the podium, a result that left him "extremely satisfied".
Pérez confirmed on 13 November 2013 that he would be leaving McLaren at the end of the season to be replaced by Kevin Magnussen. On 12 December 2013 (exactly a month after it was announced he would leave McLaren), Force India confirmed that Pérez would join Nico Hülkenberg in their driver line-up for 2014 in a 15 million Euro deal.
Sergio Pérez