Lanning played a leading role in her side's 3-0 whitewash of New Zealand in Brisbane that saw the six-time world champions to a record 21 consecutive wins in the format.
The 28-year-old aggregated 163 runs in two matches, including a Player of the Match performance of 101* in the second fixture, which helped her advance four places and dislodge West Indies captain Stafanie Taylor from the top.
This is the fifth time that Lanning has grabbed the top spot, the last occasion being in October 2018. She has been No 1 for a total of 902 days since the first time in November 2014.
Rachael Haynes, who led the Australian side in the final ODI after Lanning was ruled out due to a hamstring injury, was another batter to make quick progress. Haynes has gained seven places to reach a career-best 13th position after finishing as the most prolific scorer in the series with 222 runs that comprised knocks of 44, 82 and 96.
Left-arm spinner Jess Jonassen's eight wickets in the series, which included a haul of 4/36 in the second match, helped consolidate her position at the top of the table for bowlers with a career-best 804 rating points.
She had started the series at 754 rating points, only four points less than her previous best of 758 recorded last year.
The first time Jonassen topped the ODI bowlers' list was in July 2017 and she has been No 1 for 599 days spread over six spells, including the ongoing one that commenced in October 2019.
