Perez, who was out of contract with Racing Point, will race alongside Max Verstappen for the Red Bull team in 2021.
Max Verstappen finished 16 seconds ahead of Valtteri Bottas and 18.4 clear of world champion Lewis Hamilton as Red Bull enjoyed a rare and significant success over both Mercedes cars.
The Dutch driver edged Valterri Bottas in second and the Finn's Mercedes team-mate Lewis Hamilton, who is racing for the first time since winning the championship after contracting coronavirus, in third for Sunday's Grand Prix.
Formula 1 2020: Red Bull's Max Verstappen fastest ahead of teammate Alexander Albon in final practice for Abu Dhabi GP
Verstappen led Albon by .5 seconds and Renault driver Daniel Ricciardo by .63. Ricciardo is competing in his last race for Renault before joining McLaren next year and has two third-place finishes this season.
Formula 1 2020: Valtteri Bottas back on top ahead of Lewis Hamilton as Mercedes rule practice sessions
Bottas clocked a best lap in 1min 36.276sec to outpace Hamilton, back after a bout of Covid-19 that forced him to miss an F1 race for the first time, by 0.203 seconds.
Formula 1 2020: With future up in the air, Racing Point's Sergio Perez eyeing job at hand at Abu Dhabi GP
Perez may be without a seat in 2021 as four-time world champion Sebastian Vettel replaces him after leaving Ferrari.
Verstappen moved up the leaderboard late in the session to finish .21 seconds ahead of Mercedes driver Valtteri Bottas and .36 clear of Bottas' temporary teammate George Russell.
Formula 1 2020: Substitute George Russell upstages Valtteri Bottas to top Sakhir Grand Prix practices
Russell outpaced second-placed Verstappen of Red Bull by 0.323 seconds while Bottas struggled to deliver a clean timed lap and wound up down in 11th
Formula 1 2020: Max Verstappen tests negative for COVID-19 after coming in 'close contact' with Lewis Hamilton
The newly-crowned seven-time champion Hamilton returned a positive test result on Monday following his victory at last Sunday’s dramatic Bahrain Grand Prix, where he shared the podium and post-race media commitments with Verstappen.
Hamilton finished about .3 seconds ahead of his Mercedes teammate Valtteri Bottas and around .4 clear of Red Bull's Max Verstappen.
Verstappen in his Red Bull was .26 ahead of Hamilton and .37 ahead of Hamilton's Mercedes teammate Valtteri Bottas.
For Racing Point's Lance Stroll, this was the first pole position of his Formula One career. His teammate Sergio Perez was third.
Formula 1 2020: Racing on slick Turkish GP track was 'terrifying,' says Mercedes star Lewis Hamilton
Hamilton, who is seeking to seal a record-equalling seventh world title in Sunday's race, said his day's practice had been "a little bit of a disaster" at the Istanbul Park circuit.
Racing on the track where his childhood idol Ayrton Senna lost his life, Hamilton finished 0.097 seconds behind Bottas' time of 1 minute, 13.609 seconds.
Hamilton’s Mercedes team-mate and nearest title rival Valtteri Bottas was third, nearly half a second off the pace, ahead of Pierre Gasly of Alpha Tauri and Ferrari’s Charles Leclerc.
Formula 1 2020: Lewis Hamilton wins Portuguese GP to vroom past Michael Schumacher into record books
British driver Lewis Hamilton won his 92nd career race to move one ahead of German great Michael Schumacher.
Formula 1 2020: Lewis Hamilton pips Mercedes teammate Valtteri Bottas to pole position in Portuguese GP qualifying
In denying his Mercedes teammate Valtteri Bottas in the final seconds of qualifying Hamilton moved to within three of his 100th career pole.
Albon has struggled for consistency in his second year in Formula One with Red Bull after a mid-season switch from Toro Rosso last year, his rookie season.
After leading Friday's two practice sessions, the Mercedes driver was .03 seconds quicker than teammate Lewis Hamilton and .16 ahead of Red Bull's Max Verstappen.
French driver Pierre Gasly's car caught fire on Friday while there was a crash between Red Bull's Max Verstappen and Lance Stroll's Racing Point car.