The title was clinched at the end of the season-ending Championship Play-offs held at the Agege Stadium in Lagos.
The People’s Elephant topped the group that included Kano Pillars, Enugu Rangers, Akwa United, Lobi Stars and FC IfeanyiUbah with 12 points from five matches.
"My first statement coming to the club was to help the club gain continental glory back and bring back the glory days of Enyimba which God actually brought back for us,” Onuwa told the club's official media office.
"Since we came third in the league (at the end of the regular season) people started writing us off. But with the togetherness of the team, the management and even the help of the government we have been able to surprise them.
“The motivation was also an important factor because they never owed us anything.”
Onuwa missed the league title narrowly with his previous club, MFM two seasons ago when the Olukoya Boys finished second behind Plateau United in 2017 before he crossed over to Enyimba.