The bar announced it would be opening in 2020 just before the pandemic hit - so owners and customers have been looking forward to this day for more than two years.
It will finally open today (May 6) and is currently taking bookings via its website.
And the operators have confirmed that as well as Mr Wilson's Bar, the basement will be transformed into Capone's, where customers will need a password to get in to recreate the feel of the 1920s speakeasies.
David Henning, one of the masterminds behind the concept, said: “Mr Wilson's is actually two bars in one, set over the ground floor and basement.
"At the ground floor level is Mr Wilson's, which is a modern bar with a few special touches, like a working water wheel!
"There's two bars - one is a large island in the middle of the room and the second is much smaller, at the far end of the room. There's plenty of tables and comfortable seating, plush curtains and beautifully crafted steel features.”
He added: “In the basement it's a completely different world. We've created Capone's - a 1920s-style speakeasy in the style of the American Prohibition era. It's really special.
"I won't give too much away, but all I'll say is that everyone who's seen it has been blown away."
He said the idea of asking customers to provide a password to gain access to Capone's is "a bit of fun as a nod to the secretive nature of the speakeasies of the 1920s".
He said: "When you make a booking for a table, Mr Wilson will send you a text message confirming it.
"On the day of your booking you will receive a second text message with a unique password you'll need to gain entry to Capone's. Don't worry, we won't turn you away if you can't remember it!
"We've done our very best to make Mr Wilson's and Capone's something different and unique. We're sure that the people of Sheffield (and beyond!) will be impressed!”
The venture has created 40 new jobs.
Members of the public can also get their first drink for free in the new bar – so long as they sign up for the mailing list here https://mrwilsons.co.uk/
The venue is also launching a bottomless brunch on Saturday, May 14, for £30 per person.
You will get a choice of Mr Wilson's 'Succulent Six' dishes to start your weekend in style, as well as unlimited drinks for 90 minutes.
The name Mr Wilson’s was chosen as the building was once part of Samuel Wilson & Son Limited, which had a service station and showroom on West Street that stocked agricultural and industrial vehicles. The place displayed tractors in its front windows.