The 32-year-old all-rounder Watson was yesterday named Rajasthan Royals captain in place of the retired Rahul Dravid who was anointed the team mentor.
"Congrats to Watto on becoming Captain of the Royals, good luck to you & the boys in #IPL 7," Warne tweeted.
Warne also shared a photograph along with the tweet, showing both he and Watson wearing Royals jerseys.
Warne had led the Jaipur-based outfit to the IPL title in its inaugural edition in 2008.