Welbeck's previous contract would have run out next summer but Brighton have rewarded him following a bright start to the season.
The 31-year-old played a key role in the Seagulls' opening day win at Old Trafford, setting up Pascal Gross' opener in a 2-1 win over Manchester United.
Welbeck joined Brighton on a free transfer from Watford in the summer of 2020 and has made 51 top flight appearances for the club, scoring 12 goals.
Before signing his new contract, Welbeck had briefly been touted for a return to Manchester United, where he begun his career.
Speaking to the club's official website on Welbeck's new deal, Brighton manager Graham Potter said, "Danny has been brilliant for us from the moment he arrived. He became a part of the group quickly and has become a real leader.
"He uses his experience to help the group and is a great role model for the younger players.
"On the pitch he has been really important for us, he gives so much to the team and I am looking forward to continuing working with Danny in the coming seasons."
Speaking to BBC Radio 5 Live, Welbeck added: "I'm feeling fit. I'm feeling strong and long may it continue.
"We've got a great manager to play under and hungry players who want to improve every day. To be part of the process and trying to elevate the club to the next level is something I am looking forward to over the next few years."
Welbeck has won 42 caps for England, scoring 16 goals.
