The South African side that had eliminated the other local side Shujaa in the semi-finals and begun the game by charging hard to earn the opening try through Shaun Adendorf in the 4th minute.
Dennis Ombachi responded with a fine try after two minutes but Lavin Asego missed the resulting conversion to take the scores to 7-5.
He made it a double in the 8th after receiving a pass from Nato Simiyu who had picked the ball from an Andrew Omonde build up as the Kenyan side took a 7-10 lead in to the break.
The visitors put up a strong display in the second period with Juan Swanepoel making a try after an excellent run from the midfield in the 13th as they regained a 14-10 lead.
Omonde was on the attack three minutes later but he dropped the ball on his way to make the try much to the disappointment of the home crowd but he made amends in the 17th with a try.
However, Justin Geduld sealed the win for South Africa with a last minute try to take home the Robin Cahill trophy.
Earlier, Shujaa won the third place play offs after a 21-7 victory over Spain after tries from David Ambunya , a double from Dennis Ombachi who was the tournaments highest scorer and Daniel Sikuta.
Morans qualified for the finals after seeing off Spain in a slow paced match with the first try coming from Dennis Ombachi in the 2nd minute after a sustained build up from the midfield. Lavin Asego returned a good conversion to take the score line to 7-0 that the local team held onto the break.
The Spanish side came back much stronger but with the rousing support from the local fans at the stadium, Abunya made the second try after a pass from Ombachi just before he was tackled as he made a spirited run on the right.
In the other semi final fixture, Shujaa couldn’t tame the spirited South Africans who came all out in and managed a quick try in the first minute from Andre Warner to take a commanding 5-0 lead.
The visitors would have been 10-0 in the 3rd but skipper Collins Injera came out to the rescue to cut out their push forward towards the Kenyan touchline.
However, the visitors capitalized on a defensive blunder from the local team and made a try through Justin Geduld before following up with another from Werner Kok in the 6th as they dominated the home side.
Warner was on the rampage with another try as basic errors cost Shujaa who were trailing 22-0 as the two sides went into the break.
After the break, Biko Adema put a smile on the local fans as they tried to stage a come back with a try in the 10th after a pass from Michael Wanjala much to the delight of the crowd.
Shaun Adenhorf once again broke their heart s with a try in the final minute of the game as they triumphed 29-7 to book a berth in the final.
In other mixed results, the University Select developmental side lost the Shield Final to Zambia with a 21-15 score line while Chairman Select were defeated 26-10 by Western Province in the Bowl final
Last year’s winners Samurai lifted the Plate after a 40-14 victory over French side Grenoble.
Main Cup Final
Morans 17 -21 South Africa EPD
Shujaa 21-7 Spain
Chairman Select 10-26 Western Province
University Select 15- 21 Zambia
Samurai 40- 14 Grenoble