Making first use of the wicket after calling the coin correctly, Namibia were restricted to a modest 203 for nine in their stipulated fifty overs.
Opener Jan-Berry Burger laid a strong foundation scoring an enterprising 49 runs off 42 balls which was laced with 10 fours. Wicket-keeper Hugo Ludik chipped in with an undefeated 45.
Pace bowlers Najaf Shah, Mohammad Khalil and Kamran Sajid snared two wickets each.
Set a 205 for victory, Pakistan 'A' rode on Ashar Zaidi's sparkling 88 to romp home in style reaching 207 runs for two in just 33.5 overs.
The Rawalpindi southpaw clubbed 10 fours and a six in his knock of 88 runs from 87 balls to give the visitors a flying start. Fellow opener Faisal Athar contributed 31.
Naumanullah provided a flourish to the innings bludgeoning an unbeaten 68 off 65 deliveries studded with eight fours and three sixes.
Pakistan 'A' won the first two games by margins of nine wickets and 111 runs, respectively.
The Pakistanis will now travel to Zimbabwe where they would play two four-day games and three One-day matches.