Kohli has reached No.1 in the ODI rankings for the first time while Ajmal jumped up two places to displace Ravindra Jadeja and Sunil Narine.
The other big gainer in the bowling top ten is South Africa's Morne Morkel, who also climbed six spots to reach No. 7, the report said.
India's openers Shikhar Dhawan and Rohit Sharma, both of whom were in form against Australia, have also risen sharply in the rankings, the report added.
Kohli takes over as No. 1 from Hashim Amla, who has held the top spot since November 2010, the report further said.
Ajmal took six wickets in the first two ODIs to move past Jadeja and Narine, according to the report.