The 31 year old left St Mary's for the London Stadium in a deal worth £30M following the club's relegation to the Championship in 2023.
Having made 410 appearances for the club, scoring 55 goals including several incredible free kicks, Ward-Prowse has rejoined the Saints who are hoping to clinch promotion back to the Premier League this season.
Speaking on the move back to his boyhood club, the midfielder admits that he is over the moon as he pulls on the shirt once more.
“It feels a bit surreal. The last couple of days have been pretty intense, but I’m delighted to be back, and to be wearing the red and white again is truly special.
“It’s the place I call home, obviously having come through the Academy since I was eight. It was an incredible journey up until the point that I left, but home is a special place and I always had it in the back of my mind that it was somewhere that I wanted to be. I’m here today very excited and looking forward to the challenge ahead.”
Ward-Prowse had just one year left on his deal at the London Stadium and reports state that Southampton paid just £1M to free him from the London club.
He joins Flynn Downes, Caspar Jander and Cam Bragg in a formidable midfield under manager Tonda Eckert whose side sit dead bottom of the Championship on –1 point following last season's promotion play-off final after the major "Spygate" scandal.