The wide man, who signed from Bury foir an undisclosed fee in the summer, has had a season hampered by injury at NYS and moves back to Lancashire with the transfer window now open.
The length of the deal is not yet known, but is believed to be until the end of the season.
Millers boss Steve Evans said on Friday morning that he is working on a number of deals in an out of the club, with Kayode Odejayi already having returned to Accrington.
Ipswich winger Anthony Wordsworth has been rumoured as a replacement for Worrall to bolster Evans' squad.