The UUP has regained representation at Westminster after several years as former party leader Robin Swann won with 16,311 votes.
The seat has always been held by a unionist party, making it a key battleground between the DUP and UUP at this election.
However, the DUP came under mounting pressure during Friday’s count as word spread Mr Swann was outpolling Paul Girvan.
Mr Girvan held the seat for the DUP since 2017 after unseating the UUP’s Danny Kinahan.
However, Mr Swann reclaimed the constituency by a margin of 7,512 votes with Mr Girvan receiving 8,799 overall.
The party has made the constituency a key target in this election with Mr Swann switching constituencies to run for Westminster.
Speaking after the declaration Mr Swann said that Northern Ireland is best served by a mixture of voices.
“I want to thank the electorate of South Antrim who have placed their faith, confidence and trust in me to be their member of parliament,” he said.
“When we went the length and breadth of South Antrim and engaged with the local people on the issues that mattered to them on a local level, a national level and an internation level it was clear they were looking for change.”
There was a clear margin with ousted MP Paul Girvan receiving 8,799 votes overall.
Mr Girvan’s vote suffered a 15.7 swing compared to 2019.
Speaking after his defeat he thanked his family and election team.
“Over the last seven years, we’ve had the pleasure of working in what has been, I believe, the premier constituency in Northern Ireland,” he added.
“South Antrim has been a swing constituency in the past and the DUP have won this seat back before and we haven’t went away. We will be back.”
Sinn Fein came in third in this year’s election with 8,034 votes, building on the gains in local and Assembly elections.
Alliance John Blair finished fourth with 4,574 votes.
SDLP councillor Roisin Lynch returned as her party’s candidate. However, the SDLP has suffered a steady decline in votes here for almost two decades, with the share falling each Westminster election. Ms Lynch received 1,589 votes, down from the 2,288 in 2019.
Aontú and the Green Party fielded Westminster candidates for the first time were unable to deliver any significant results. Aontu candidate Siobhann McErlean received 376 votes while Lesly Veronica collected 541 for the Green party.
Despite a higher number of eligible voters when compared to 2019 voter turn out dropped by almost 4% to 55.92%.
