The 2020–21 season was Partick Thistle's first season in the third tier of Scottish football in Scottish League One, having been relegated from the Scottish Championship at the end of the 2019–20 season. On 15 April 2020, the SPFL voted to end the lower leagues in Scottish football due to the coronavirus pandemic and as a result Partick were relegated to League One after two years in the Championship, which the club decided not to take legal action against. Partick Thistle also competed in the League Cup, and the Scottish Cup.