The unsettled centre-half was recalled from a third loan spell at Wigan earlier this month, with the deal which saw him head to the Latics on a season-long loan last August having an option enabling the Millers to recall him by a cut-off point of January 15.
The club elected to invoke the clause, putting the immediate future of the 30-year-old in limbo.
Now, after several rounds of negiotations, a fee has finally been agreed between the Millers and Wigan to enable the former Blackpool player to head back across the Pennines on a permanent deal.
Tilt, who arrived at Rotherham in the January transfer window in 2020, made just one senior appearance for the club.
That arrived in the 2019-20 season - curtailed due to the Covid-19 pandemic, while a glute problem ensured that he had to bide his time for his debut.
After spending two loan spells last term at Wigan, a hamstring injury hindered Tilt's progress in pre-season back at Rotherham and he was allowed to return to the DW Stadium.
The Millers would like to bring in one new face before the transfer deadline next week, while the future of transfer-listed striker Freddie Ladapo remains uncertain.