The Ugandan joins Celtic from the University of Pretoria, who finished in 13th position this past season.
The club reported that Massa will join in the pre-season and officially be introduce to the Celtic Supporters together with the other new signings before the 2015/16 PSL season kicks off.
“We are happy that we managed to sign a top player like Massa. This goes to show that we are serious about our mission to reinforce the squad and challenge for a respectable position on the log.
“His experience and prowess will assist us in achieving our goal,” Celtic’s chairman Max Tshabalala said on the club’s website.
Massa netted eight league goals for Tuks in a season where they again finished outside the top eight. Failing to match the record they achieved during their first season in the top flight in 2013.
Tshabalala also hinted that the club will sign more quality players who have been identified by the technical team.