They were declared winners of the final under an Asian Games-specific rule where the higher-ranked team takes the honours if the match cannot be finished, in this case due to rain.
Afghanistan made 112-5 under the floodlights in Hangzhou before the wet weather arrived after 18.2 overs. With conditions not improving, the final was abandoned.
It completed a golden double for India after they beat Sri Lanka by 19 runs to be crowned women's champions last week.
"It feels good, we're very proud, wearing a medal is not something we're used to and it's emotional for everyone," said India skipper Ruturaj Gaikwad.