Having taken 3-53 in the Kenyan innings, he returned to hit the winning runs that helped Bangladesh hold off a resurgent Kenyan side buoyed by a tight pace-bowling attack.
Dangerman Thomas Odoyo had raised the local hopes when he spearheaded the fightback by ripping through the Bangladesh middle order which brought him 4-36 to add to his career best 84 with the bat.
The tourists needed 51 runs to win when Mortaza took to the crease after stand-in skipper Khaled Mashud was caught at square leg and he held the side together with a 43 to help guide Bangladesh to 185 for eight in 46 overs.
Afterwards Mortaza, who earned himself the man-of-the-match award for the second sucessive match, said he was satisfied with their performance.
"We tried to play well and tried to play positive. That was there for everyone to see," said Mortaza. "I am very happy to have played my part in the victory."
Kenyan captain Steve Tikolo said he was looking forward to winning the third and final match on Tuesday.
"Tuesday will be an important day for us. We look forward to come back and try and win the last game," said Tikolo.