The 2020–21 season was Portsmouth's fourth consecutive season in EFL League One, Along with League One, the club also participated in the FA Cup, EFL Cup and EFL Trophy.
Due to the COVID-19 pandemic in the United Kingdom, all games for the season were played behind closed doors without supporters present, except for two matches in December 2020 that were limited to a maximum capacity of 2,000 supporters.
The season covers the period from 1 July 2020 to 30 June 2021.
The draw for the first round was made on Monday 26, October.[37] The second round draw was revealed on Monday, 9 November by Danny Cowley.[38] The third round draw was made on 30 November, with Premier League and EFL Championship clubs all entering the competition.[39]
The first round draw was made on 18 August, live on Sky Sports, by Paul Merson.[40] The draw for both the second and third round were confirmed on September 6, live on Sky Sports by Phil Babb.[41]
The regional group stage draw was confirmed on 18 August.[42] The second round draw was made by Matt Murray on 20 November, at St Andrew's.[43] The third round was made on 10 December 2020 by Jon Parkin.[44]