However, the course soon fell into disrepair due to the owning company having been taken over by the state between 1975 and 1978, and a significant redevelopment effort was needed before international motorsport returned in 1984.

[4][5] Estoril became a popular event on the F1 calendar, the setting for many well-known moments including Niki Lauda winning the 1984 championship, his third and final, from McLaren teammate Alain Prost by just half a point by finishing second to Prost at the 1984 Portuguese Grand Prix; three-time world champion Ayrton Senna's first F1 win in 1985; Nigel Mansell's notorious black flag incident and subsequent collision with Senna in 1989; Riccardo Patrese being launched airborne in a near-backward flip after colliding with Gerhard Berger on the main straight in 1992; and Jacques Villeneuve overtaking Michael Schumacher around the outside of the final turn in 1996.

After the death of Ayrton Senna at the 1994 San Marino Grand Prix, a chicane was added which increased the circuit length to 4.360 km (2.709 mi).

[2] A new redesign of the parabolica turn which saw its length reduced to 4.182 km (2.599 mi) was implemented in 2000 in order to obtain FIM homologation.

As of January 2025, the fastest official race lap records at the Circuito do Estoril are listed as: