Sporting director Mike Cave welcomed the new deal, saying: "We rate James very highly and we're delighted that he has committed his long-term future to the club. He had a successful loan at St Andrew's last season and he is returning to an environment he knows well. We wish him all the best for the season ahead."
The move marks the 22-year-old's third consecutive full campaign in the second tier, having previously spent a season and a half on loan at Sheffield Wednesday before his year at Birmingham. Manager Chris Davies praised Beadle's progress on the club website.
"When he earned his opportunity last season, he established himself and I thought his performances continued to improve as the campaign went on. He's still only 22 but already has significant Championship experience, and those experiences will only make him a better goalkeeper.
"Every season he has played at this level, he has continued to develop, and we're looking forward to helping him take the next step again this year," Davies said.
Elsewhere at Falmer stadium, winger Rodrigo Rego has joined La Liga 2 side Castellón on a season-long loan after signing for Brighton earlier in the transfer window from Benfica on a five-year deal. Cave also commented on the 21-year-old's move to Spain, saying: "We have high hopes for Rodrigo and we're looking forward to seeing him get the opportunity to play regularly at first team level. We will monitor his progress closely throughout the season."
Rego came through the academies of Porto and Famalicão before joining Benfica in 2023, where he made his senior debut as a late substitute in a 2-0 Champions League win over Ajax in November, following it up with his first league start four days later in a 2-1 win over Nacional.
Both moves reflect Brighton's broader strategy of blending long-term investment in emerging talent with carefully managed loan spells designed to accelerate their development at senior level before they are considered ready for regular first-team football at the Amex, a pathway that has become a defining feature of the club's recruitment model in recent years.