The firm has pledged to stay put in its Orchard Square shop until at least March 2026, despite interest from other property owners.
It also changed its contract with London & Associated Properties, removing a break clause that would have allowed the retailer to leave Orchard Square after August 2018.
The company is paying £475,000 a year to London & Associated Properties.
The property firm’s chief executive officer John Heller said: “This re-geared lease reinforces Orchard Square’s position as one of Sheffield’s pre-eminent retail locations and reflects our anchor tenant’s commitment to the centre.
“Although TK Maxx has been a tenant for many years, the current 46,000 sq ft store was created for it in 2008 as part of our continual asset management programme that has improved and upgraded Orchard Square’s retail offer.
“The unit has always traded successfully and by extending the lease we are ensuring TK Maxx’s presence is maintained at the centre. We were aware that the retailer had been approached by other city centre property owners but ultimately it considered Orchard Square as its preferred fashion location.”
No-one from TK Maxx was available to comment.
But the news was welcomed by Sheffield Council’s executive director for place at Simon Green.
He said: “This is clearly good news and shows TK Maxx’s confidence in its Orchard Square store and its commitment to Sheffield city centre.”
TK Maxx is the latest in a number of retailers to show faith in Sheffield. Among those now confirmed for the new development on the Moor is Ann Summers, with names such as Primark and Game moving from existing city centre units.
More names are likely to be revealed later this year.
A planning application for the long-awaited Sheffield Retail Quarter is expected to be unveiled in the coming months.
And outside the city plans for a £300m expansion of Meadowhall will go on show to the public on Friday.