Tony Warner, 43, joins head coach John Gregory's coaching staff which already includes assistant coaches Mark Lillis and Syed Sabir Pasha.
The MoU was signed after a brief presentation by each of the three north-eastern clubs. Goa was represented by Sujay Sharma, Head of Player Recruitment and Analysis.
In 2014-15, he went to Spain to coach Segunda Division club Real Zaragoza where he led the team to finals of the La Liga play-offs. A season later, he joined Thai Premier League Champions Buriram United FC where he won the Thai League Cup and Mekong Club Championship.
ISL 2017-18 will be expanded to 10 teams and a total of 95 matches will be played this season with the first match scheduled on November 17.