The 22-year-old has put pen to paper on a four-year deal which runs until Jun 2027, and the Seagulls have the option to extend it by a further 12 months.
Rushworth is yet to make his senior debut for Brighton and spent the last two seasons on loan at Walsall and Lincoln City, keeping 19 clean sheets in 42 League One appearances for the latter last season.
The Halifax-born shot-stopper will now test himself in the Championship on a temporary basis with Swansea where he is set to challenge Andy Fisher for the number one jersey.
"Carl has improved year-on-year with loans in non-league, League Two and League One," Brighton's technical director David Weir told the club's official website.
"Now he is making another step up which is a really exciting prospect for him - we're looking forward to seeing how he progresses over the next year with Swansea."
Rushworth, an England Under-21 international, is expecting a "tough" challenge in the Championship, but he is looking forward to working under new manager Michael Duff and head of goalkeeping Martyn Margetson, who also works as the goalkeeping coach with the England national team.
"I think the Championship is the toughest it's been for a long time with the teams it's got in it, but I'm looking forward to it," Rushworth told Swansea's official website. "I'm expecting it to be tough. There's never an easy game, just like there isn't one in League One or League Two.
"I'm just going to thrive off the challenge and experience of playing some of these games against some of these teams, and I'm really looking forward to it and pushing myself because I feel this is the next challenge I need in my career.
"As a squad I think we want to be pushing to be as high as we can. I think that's going to be on everyone's mind and we're going to be working together to achieve that.
"Personally, I want to stay fit for the season, play as many games as I can and beat my clean sheet record that I got last season. I'm buzzing for the start of the season. I've been waiting for it to come around ever since I heard Swansea were interested. I can't wait to get started."
Rushworth, who will wear the No.22 shirt for Swansea, added: "I'm buzzing to get it done. After speaking with Marge (Margetson) I just wanted to be here and get in the building.
"I think it's the perfect club for my progression. I think taking the next step up into the Championship is what I needed.
"After speaking with Marge from the start, with the experience he's got and the amount of games I hope to play this season, it's a no-brainer really.
"There're so many positives it would be foolish of me to turn it down. For me to be in Marge's eyeline every single day, he'll be giving me all the advice he can give me.
"I think it's going to be very beneficial for my career as well to have the England senior goalkeeping coach working with me."
Swansea have also confirmed the signing of Ukrainian striker Mykola Kuharevich from French side Troyes for an undisclosed fee, with the 22-year-old penning a three-year contract.
Both Rushworth and Kuharevich could make their Swansea debut when the Welsh club play host to Birmingham City in their opening Championship match of the new season on Saturday.