The two top-flight teams are ready to lock horns and Javi Gracia's side is gunning for their first Cup title.
Ighalo had played for the Hornets between the years 2014 and 2017. He has backed his former team for glory and also praised them for their journey to the last stage of the competition.
"FA Cup final today. Big game for Watford," Ighalo tweeted.
"I’m excited and nervous at the same time but whatever is the outcome of the game today, you lads have done well and deserve everything. Good luck guys."
FA Cup final today.Big game for @WatfordFC I’m excited and nervous at the same time but whatever the outcome of the game today,you lads have done well and deserve everything.GOOD LUCK guys🐝🐝🐝🙏🏾 pic.twitter.com/7lAD66hZPw— Odion Jude Ighalo (@ighalojude) May 18, 2019
During his two-and-a-half -year stint at Vicarage Road, the 29-year-old helped Watford gain promotion to the English top-flight in 2015.
He later went on to score 31 goals in 98 Premier League appearances before leaving for China in January 2017.
The Super Eagles have been drawn in Group B of the football showpiece in Egypt with matches against Guinea, Madagascar and Burundi.