South Africa will next play Sri Lanka in their third Group 1 match on October 30, while West Indies will take on Bangladesh a day earlier.
Lewis (56) and Lendl Simmons (16) got West Indies off to a flier.
In a big upset for South Africa, Quinton de Kock is not be available for the match due to personal reasons, making way for Reeza Hendricks.
Lizelle Lee combined with Dane van Niekerk in an opening stand of 53, before the skipper fell to Qiana Joseph.
Kieron Pollard has said his side would have a fair idea about Australia and South Africa heading into the T20 World Cup.
South African Skipper Bavuma said that they will have to come with a better attitude and make sure that they focus on execution.
West Indies was already under pressure after fast bowler Kagiso Rabada's three wickets at the top of the order.
Kagiso Rabada is glad that he has finally broken the jinx and taken a five-wicket haul in 33 innings since Match 2018.
Quinton de Kock came out to bat at the MA Chidambaram Stadium sporting a unique design on his shoes, which showcased the 'vulnerable' species.
South African pacer Kagiso Rabada claimed his 10th five-wicket haul as the visitors thrashed West Indies by an innings and 63 runs.
After being dismissed for 97 on the first day, the West Indies slumped to 51-4 as it began its second innings 225 runs behind South Africa.