The Young Lions face leaders Slovakia in Kielce on Monday knowing anything other than victory could dent their hopes of topping Group A.
Only the three group winners and best runners-up progress to the semi-finals and Slovakia are already two points clear after they beat host nation Poland 2-1 on Friday following England's 0-0 draw with Sweden.
Southgate arrived in Kielce on Friday and has spent the weekend with the squad ahead of Monday's crucial outing.
Ward-Prowse was also captain for the Under-21s under Southgate - who gave the 22-year-old his senior debut in March - and revealed Southgate has been helping to guide the squad.
"He's been around and spoken to us, pulled us aside individually and seen how we are, and it's great to have him and Steve (Holland, assistant) around," said the Southampton man. "They played a massive part in our qualifying campaign to get us here.
"He wants to show us support and give us that confidence. It was great to see him here, to show us there is a pathway for young English players.
"We have a lot of friends in the seniors now and it is a time for us to show him what we can do individually and as a team."
While Ward-Prowse has been away Southampton sacked Claude Puel as manager but the midfielder is refusing to let the St Mary's uncertainty upset his plans with England.
He said: "It is one of those things and it is a decision from the club that has been made. Claude was very good to me, he gave me lots of opportunities and I got into the England squad while playing under him.
"I have got nothing but thanks for him. But my main focus at the minute is the tournament and making sure I am in the best way mentally and physically to help the team. I haven't spoken to him.
"The tournament is the main priority, as I said. It seems to happen every summer (that Southampton lose their manager) but that is the way football is sometimes.
"It is up to us as players to deal with it. The club and the players have shown that we can cope with managers and players going."
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