The first season of the British Touring Car Series (also known as the BTCS) was held from November 2025 through to January 2026, and was known as the Winter 2025/26 season. Organised and run by Lame Sheep Racing, the league used TCR cars across British circuits from the iRacing.com Simulation service.

As the inugural season to the series, there were multiple changes made throughout the season, such as reducing the amount of drivers involved in the inverted grid in the third race of the night, and the introduction of an incident limit.