Chawrasia, who till the 17th hole on Saturday, was in hunt for a top-10 finish but crumbled thereafter.
He bogeyed 17th and 18th on Saturday and then shot a seven-over 78 to finish at a total of five-over 289 and in 50th place.
Lahiri's luck or putting did not change as he carded one-over 72 and ended at 10-over 294 and in tied-57th place.
On a sun-drenched final day, in front of a sell-out crowd at Reserva de Marapendi Golf Course, Rose added the Olympic crown to his 2013 US Open title after a prolonged and exciting battle down the stretch with Sweden's Henrik Stenson.
In the end, the packed grandstand which turned the 18th arena into a noisy sporting amphitheatre, watched spellbound as Rose got up-and-down from the side of the green for the birdie which sealed a worthy gold medal performance.
Stenson, who emerged on top after a similarly epic shoot-out with Phil Mickelson in The Open at Royal Troon last night, had to accept second place this time and the silver medal was a deserving reward for his part in a wonderful spectacle which saw Matt Kuchar of the United States claim the bronze medal after a course record-equalling last round of 63.
Rose finished with four rounds in the sixties and his closing 67 secured the gold medal with a 16-under-par total of 268.
The leading three players completed the 72-hole test detached from the rest of the field, in which Belgium's Thomas Pieters finished a highly creditable fourth after slicing 12 shots off his third-round 77 with a final day 65.
After holing out for a birdie four on the 18th, Rose punched the air in celebration and fell into the arms of his wife, Kate, before savouring the medal ceremony.
"Olympic gold medalist - It sounds absolutely incredible," said the 36-year-old.
"I pretty much just need the multiple major now, but for the most part, I'm there on that quote.
Disclaimer: No Business Standard Journalist was involved in creation of this content
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