Celebrity Big Brother 21, also known as Celebrity Big Brother: Year of the Woman, was the twenty-first series of the British reality television series Celebrity Big Brother. It launched on 2 January 2018 on Channel 5, and concluded on 2 February 2018 after 32 days, making it the joint longest series to date. It is the fourteenth celebrity series and the twenty-first series of Big Brother overall to air on Channel 5. Emma Willis returned to host the series, while Rylan Clark-Neal continued to present Celebrity Big Brother's Bit on the Side.
On 2 February 2018, Shane Jenek / Courtney Act was announced as the winner of the series having received 49.43% of the final vote, with Ann Widdecombe as the runner-up after receiving 39.50%.