Watson was reinstated last week after being suspended indefinitely in January due to ongoing issues with alcohol abuse.
Watson finished Stage 2 of the NHL's substance abuse and behavioral health program and had entered the follow-up phase.
Watson, 27, was not paid during the suspension.
It was Watson's second suspension of the season. He missed the first 18 games after pleading no contest to a domestic assault charge in July. Watson was initially suspended for 27 games by the NHL, but an arbitrator reduced it to 18.
Watson has seven goals and six assists (13 points) in 34 games for the Predators this season.
Forward Miikka Salomaki was also assigned to the Milwaukee Admirals under the same designation.
--Field Level Media