The veteran centre-back arrived at Old Trafford last term to partner Harry Maguire, but a run of injuries saw him muster just 22 league games in all, robbing United of some much-needed stability at the back.
While England international Maguire often shouldered much of the ire, supporters were also left frustrated by Varane's fitness issues, and wondered what role he would play this term under new management, particularly with the arrival of Lisandro Martinez.
But Ten Hag believes having the FIFA World Cup winner at full fitness will only aid his squad, adding that he constructed a specialised pre-season training plan in order to help bolster the 29-year-old's prospects.
"[I'm] 100 per cent convinced [we'll see his best]," the Dutchman stated ahead of his side's Premier League opener against Brighton and Hove Albion.
"During pre-season, we built a careful and individual training plan. In the last three weeks, he has been involved in every session on the pitch, I am really happy about that.
"You see him growing, his fitness levels and also his performance levels. I am happy about that as, at the moment, Rapha will be fit and it is a huge boost for both the squad and the team."
Elsewhere, Ten Hag addressed his desire to balance both a commitment to victory and an appreciation for attractive football, after United struggled for both results and flair last term under Ole Gunnar Solskjaer and Ralf Rangnick.
"A Dutchman, they always want to play attractive football," he said. "That's why I am here and I like it. You want to win, but you also want to win in a certain way, being proactive, brave and with adventure.
"That is also what belongs to the culture of Man Utd, we want to bring it in but, at the end of the day, if you cannot win in a good way or an entertaining way, you still have to win.
"That is the mentality and the attitude that we have to bring in. Of course, there will be games where you will not play well but you still have to win."