Last looking down from the top in January 2018, BabarAzam has played a pivotal role in Pakistan's T20 World Cup charge, making 198 runs across four innings, averaging 66 at a strike rate of 124.52.
Sitting in second in last week's rankings, Babar moved up 14 points (to 834), pushing past Dawid Malan, who slid from 831 to 798.
Pakistan have made the ideal start to the tournament, winning their first four matches in style with Babar at the helm.
Elsewhere in the batting rankings, Jos Buttler made a jump of eight spots to 9th off the back of his 214 runs in UAE - the most across the tournament. Aaron Finch (733 points) has moved up three places to third.
Other big climbers with the bat include Jason Roy (up five places to 14th), David Miller moving up six places to 33rd, and South African captain Temba Bavuma, leaping 35 spots to 52nd on the list.
There was also a change at the top of the T20I bowling rankings, with Wanindu Hasaranga overtaking Group 1 tournament rival Tabraiz Shamsi of South Africa.
Taking 14 wickets in Sri Lanka's seven T20 World Cup matches thus far, Hasaranga claimed a hat-trick against South Africa, doing his damage at an economy of just 5.26. Other big movers include South Africa's Anrich Nortje (up 18 spots to 7th), teammate Dwaine Pretorius (up 65 spots to 34th) and Shoriful Islam of Bangladesh, leaping 77 places to 38th.
The closest rival to Hasaranga's tournament-leading haul is Shakib Al Hasan, who will miss the rest of the tournament through injury. For now, Shakib still sits atop in the all-rounder rankings, though shares the spot on the podium with Afghanistan's Mohammad Nabi. Hasaranga, also making contributions with the bat, has climbed to fourth.
Liam Livingstone's bowling impact for England has led to a 57-place jump, with Namibia's David Wiese (up 22 places to 18th) on a quest to join teammate JJ Smit (3rd) in the top ten.