It was the Mailmen who started strongly and their efforts paid dividends when former Ulinzi Stars forward Elijah Mwanzia connected a rebound. K'Ogalo looked lost and were uncharacteristically off colour.
The champions could have lost by a bigger margin, if not for the wastefulness in front of goal.
"I am satisfied with my players because we are developing with every match," Rangers coach Omollo told Goal after Saturday's game.
"We drew 0-0 with Tusker FC in our initial pre-season friendly, before registering a 1-0 loss to Gor Mahia. However, we have rectified our mistakes and you could see on the pitch.
"My defense was strong throughout and we managed to keep a clean sheet. Gor Mahia are a tough team and when you get a win plus a clean sheet against them, definitely it shows we are doing okay.
"I feel we are ready for the start of the season."
The first match was between the Mailmen and Simba wa Nairobi and the Omollo-led charges put up a good fight to win by a solitary goal scored by former Sofapaka FC player Ezekiel Okare.
In the second match against K'Ogalo, the newly promoted FKF Premier League side managed to show an improved game. They managed to win a penalty early on but Anthony Kimani, who is commonly referred to as Muki, failed to convert it.
However, it mattered less as former AFC Leopards defender Abdalla 'Shittu' Salim headed in an opener in favour of City Stars.
The Kangemi-based side conceded a penalty in the second half to ensure the spoils were shared.
The Football Kenya Federation (FKF) Premier League will kick-off next weekend.