Afridi took 3-25 and Zimbabwe struggled to 136-5 in their reply. Afridi also earlier made 23 not out with the bat, while opener Ahmed Shehzad top-scored for Pakistan with 70 from just 50 balls.
Zimbabwe captain Brendan Taylor was 32 not out in the chase but the home batsmen couldn't launch an attack after opener Vusi Sibanda was bowled by Afridi for 31, his leg stump sent cartwheeling out the ground. The legspinner removed Elton Chigumbura's middle stump for his third wicket to make certain of Pakistan's tour-opening victory in first of two T20 games.
Earlier, Shehzad kept Pakistan's innings going after the touring team initially slipped to 51-3 with the loss of Umar Amin in the ninth over. Shehzad eventually struck six fours and a six to anchor the tourists' winning total.
Pakistan had hit trouble when Nasir Jamshed was out for 2 in the second over and captain Mohammed Hafeez dismissed for 3 in the fourth over to leave it 21-2. But Shehzad took control with his second T20 half-century and had put Pakistan back on course when he was out in the 18th over to Shingirai Masakadza at 135-5.
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Seamer Tendai Chatara took 2-30 off four overs for Zimbabwe's best bowling figures and offspinner Prosper Utseya delivered four well-controlled overs for his 1-15.
Sibanda and Hamilton Masakadza made a reasonable start to the host's chase, but after Sibanda fell to a quicker delivery from Afridi for 80-2, the Zimbabweans couldn't come back.
Timycen Maruma (10) and Sibanda fell in the same Afridi over and although Taylor survived to the end, he hit just three fours. Zimbabwe needed 32 off the last over to win but managed six singles to underline the lack of threat.