The newly promoted side want to sign the 27-year-old midfielder from QPR this summer.
Sky Sports reports that a fee of just over £3 million has been agreed by both clubs.
Now it is a matter of sorting the final details and personal terms with the player.
Wilder, who scored eight goals in 48 games last term, is an attacking midfielder.
He will be a key signing for Sheffield United, who want to build a squad capable of staying in the Premier League next season.