Ramsdale, previously of AFC Bournemouth, agreed a four year contract with the club where he started his professional career having undergone a medical earlier this week.
An England under-21 international, Ramsdale’s arrival fills the void created by Dean Henderson’s departure following two seasons on loan in South Yorkshire.
The Manchester United player is being tipped to represent his country at next summer’s European Championships; with Wilder predicting Ramsdale has the potential to eventually join him in Gareth Southgate’s senior squad.
Josh Windass offers to help ‘in the doghouse’ Sheffield Wednesday fan after viral trick on girlfriend
Mass changes in Sheffield Wednesday’s potential line-up for Carabao Cup clash with Sunderland
Who is Luke Cook? Sheffield Wednesday new signing included in squad for Sunderland
Changes made at training ground as Sheffield Wednesday injury investigation continues
Sheffield Wednesday-linked striker ‘set for League One rivals’ after Darren Moore distancing comments
“Aaron is right up there with the very best young ‘keepers in the country,” he said. “I didn’t want to let him go at the time, because he was a great player, but we had to because we needed to build. He'll grow and he'll keep on getting better."
Ramsdale, who is thought to have cost an initial £10m, progressed through United’s youth system before moving to Dorset midway through their 2016/17 League One title winning campaign. He made two appearances under Wilder but switched to Bournemouth when Wilder conceded it would be wrong to deny him an opportunity to play at the highest level. However, with United eventually joining them in the top-flight, Wilder swooped when Bournemouth were relegated last month. Ramsdale joins Wes Foderingham in what is expected to be a new look United squad, after the former Rangers goalkeeper was unveiled before the end of last term.