The wicket-keeper was put through his paces during a fitness test at Wantage Road on Wednesday morning, and has been included in the group for the four-day clash.
Also recalled to the squad after missing the trip to Yorkshire is seamer Nathan Buck, with Emilio Gay, currently playing for the second team at Kent, dropping out from the 13 that travelled to Headingley last weekend.
Rossington missed the match at Leeds after damaging finger ligaments while keeping in the win over Glamorgan, and providing he suffers no reaction to his Wednesday wokout looks set to return.
That will bolster a batting line-up that has been struggling for consistency so far this season.
There have been a couple of big totals, as well as a couple of centuries apiece for Ricardo Vasconcelos and Rob Keogh, but there have also been some collapses, particularly in the first innings of matches, and batting coach John Sadler wants to see fewer of those!
“Some of the performances the batters have put in have been outstanding this year, and they’ve all shown glimpses of what they can do," said Sadler.
"What I’m looking for are some good partnerships, solid performances and some consistency in that top six, but we’ve seen we bat all the way down.
“We just need to show some more consistency really, but as a batting unit I’m pretty pleased with where we’re at, they’re striking the ball well, their work ethics are all really good.
"We just need that little bit of fortune and the batting unit can keep firing.”
Northants go into the game against Sussex in fourth place in Group 3, just four points behind third-placed Sussex who boast an identical record to Northants of one win, one draw and two defeats.
Like Northants, those losses have come at the hands of top two Lancashire and Yorkshire.
Sussex have named a squad of 13 for the encounter, and they are set to hand a debut to Australian Test batter Travis Head after he completed his spell of quarantine following his arrival in the UK last week, but there is no place for England fast bowler Jofra Archer.
He will instead to continue playing for Sussex IIs in their match with Surrey at Hove.
Ollie Robinson does return to the squad though, having been rested for last weekend's match with Lancashire.
The seam bowler claimed 20 wickets in Sussex's first three clashes of the campaign, including a match-winning nine for 78 against Glamorgan at Cardiff.
Off-spinner Jack Carson has also impressed this term, claiming 18 wickets at 21.50 apiece, while the main man with the bat for the south coast side has been Tom Haines.
He leads the Sussex run-scoring charts with 474 runs at 59.25, having scored a century and three 50s.
Northants squad to face Sussex: Adam Rossington (c/wk), Gareth Berg, Nathan Buck, Ben Curran, Brandon Glover, Rob Keogh, Simon Kerrigan, Wayne Parnell, Luke Procter, Ben Sanderson, Tom Taylor, Charlie Thurston, Ricardo Vasconcelos, Saif Zaib
Sussex Squad to face Northants: Ben Brown (c/wk), Jamie Atkins, Jack Carson, Tom Clark, Henry Crocombe, Tom Haines, Travis Head, Stuart Meaker, Delray Rawlins, Ollie Robinson, Joe Sarro, Aaron Thomason, Stiaan van Zyl