The Black Cats’ disappointing start to the season continued, as they went down 2-0 to the Cherries at the Vitality Stadium.
Callum Wilson put Bournemouth in the lead after just four minutes when he fired home from Dan Gosling's pass. Matt Ritchie made it 2-0 to the hosts five minutes later with a sensational volley.
Sunderland ended the game with 10 men following the dismissal of defender Younes Kaboul.
Borini, who joined the Black Cats from Liverpool in the summer transfer window, started the game and played until the 72nd minute, and he was disappointed with the final result.
Over the course of the 90 minutes at the Vitality Stadium, visitors Sunderland had 47% of the possession, took nine shots of which two were on target, and earned three corners.
Dick Advocaat’s side are at the foot of the Premier League table at the moment with just two points from six matches.