Rushworth made 46 Championship appearances for Coventry last term, keeping 17 clean sheets as the club secured promotion, ending a 25-year absence from the Premier League.
Financial details were not disclosed, although British media reported that Coventry paid around 22.5 million pounds ($30.26 million) for the 25-year-old.
Rushworth joined Brighton from Halifax Town in 2019 but never made a senior appearance, spending his seven years at the club on loan at six teams.
"There’s excitement. I can finally relax knowing it's done and that I’m back with the boys and at a club I loved being at," he said in a statement.
"I'm excited to have this new challenge in the Premier League and to be able to call this place home is a big thing I've been looking forward to."
Coventry begin their Premier League campaign at champions Arsenal on August 21st.