The presenter – who co-hosts the show with Noel Fielding – made the announcement on Thursday, revealing she was leaving to focus on other work commitments.
She explained: “When stepping down from a job it is quite common for people to say they are doing so in order to spend more time with their family.
“Unusually I am departing from the Great British Bake Off so I can spend more time with my other work. As my waistline will testify, Bake Off is an all-consuming show.”
“Spending time with Prue, Paul and Noel has been one of the great pleasures of my life. These are friendships which I know will continue beyond the confines of television,” she added.
“Bake Off is a wonderful programme which has already proved it can happily withstand a change of hosting personnel. The reason for that, of course, is that the true stars of the show are the bakers themselves. I wish everyone well.”
In a press statement, Channel 4 revealed the “hunt is currently on” for Sandi’s replacement, joking: “Candidates must have experience of mopping up spills and the occasional tear, making tea and keeping the amateur bakers to time.
“More information will be announced in due course.”
Sandi and Noel took over as presenters of the Great British Bake Off when it made the jump to Channel 4 in 2017.
They replaced Mel and Sue, who had hosted the show during its seven-series tenure on BBC, but chose not to stay with it when it moved channels.