The 22-year-old Nigerian forward has been impressive for Watford this season and has decided to renew contract after manager Javi Gracia put pen to paper to extend his stay at Vicarage Road.
The Hornets brought Success to English football after impressing at Spanish La Liga affiliate Granada but has failed to live up to expectations.
This season however marked a change of fortunes for Success after returning on loan at Spanish La Liga side Malaga.
Success has been behind Andre Gray and Troy Deeney in the pecking order but has rising to the occasion when called upon to deputise based on form or injury such as goal against Reading and and .
Watford announced his contract renewal through a message on their official website.
The message by Chairman & CEO Scott Duxbury said “This is a just reward for Isaac's continued hard work and application this season.
"We look forward to seeing him develop further over the coming years.”
Success scored his first Premier League goals of the season against Huddersfield and is expected to make an appearance when they take on Leicester City in their next Premier League fixture on Saturday, December 1.