The 20-year-old was introduced as a second-half substitute by Ronald Koeman in their clash with Hull City with the game all-level.
And Ward-Prowse opened the scoring from the penalty spot before Graziano Pelle added a late second at St. Mary's where Ryan Bertrand also figured as the Saints moved up to sixth spot in the table.
Shelvey celebrates his equaliser for Swansea City against Everton
In the day’s early game in South Wales, Three Lions and Swansea City midfielder Jonjo Shelvey also scored with a penalty as they drew 1-1 with Everton.
A first-half strike from Aaron Lennon had put Roberto Martinez’s side in front at the Liberty Stadium, with England stars Ross Barkley, Leighton Baines, Phil Jagielka and John Stones all featuring for the Toffees.
England and Tottenham Hotspur quartet Harry Kane, Danny Rose, Andros Townsend and Ryan Mason were all left frustrated at White Hart Lane, as former Spurs boss Tim Sherwood led his Aston Villa side to a 1-0 win in north London.
Three Lions midfielder Fabian Delph was in the Villa line-up, with Christian Benteke scoring the winner.
In the Championship, two of Ward-Prowse’s U21 squad-mates were also on the scoresheet as Patrick Bamford netted in Middlesbrough’s 2-0 victory over Rotherham United and Alex Pritchard scored for Brentford in their 1-1 draw at Derby County.
And England U19s winger Demarai Gray scored the winner for Birmingham City in their 2-1 victory against Midlands rivals Wolverhampton Wanderers at St. Andrews, where Benik Afobe had opened the scoring for the visitors.
