They surpassed the previous record of 263-5, set by Royal Challengers Bangalore in 2013
Rizwan battled through the 20 overs after Pakistan won the toss, helping his side to 165-3 on a slow surface.
Zimbabwe replied with 141-7, falling well short of the target as Pakistan claimed a 2-1 victory in the series.
In-form Rizwan, whose runs came off 60 balls, featured in a 126-run second-wicket partnership with captain Babar Azam who made 52 runs off 46 balls.
When Marumani was bowled by Mohammad Hasnain for 35, however, the runs dried up and wickets tumbled regularly as Pakistan completed a comfortable victory.