Virk qualified in the men's single sculls (M1X) while Manjeet and Sandeep made the cut in the lightweight men's double sculls (LM2X) after staving off stiff competition from the other Asian giants.
London will be Manjeet's second appearance in the Olympics, having rowed in the same event at the Beijing Games in 2008.
This is the fourth time in a row Indian rowers have qualified for Olympics.
"Previously we had participated in Athens, Sydney and Beijing. This is indeed a very proud moment for Indian rowing," said M V Sriram, secretary-general of the Rowing Federation of India (RFI).
"It speaks volumes of the systematic training of the team by our national coach and Dronacharya awardee Ismail Baig who had toiled hard with the rowers and honed them excellently," he added.
The women rowers came close but could not make the cut. PTI AH