Second seed Sharapova opened her campaign on Monday with the same scoreline against fellow Russian Olga Puchkova and completed 92nd-ranked Doi's humiliation in 47 minutes.
Doi, raising ironic cheers from the crowd at Hisense Arena with every point she won late in the contest, surrendered the match by slamming a shot into the net to hand Sharapova a virtual walkover.
Sharapova will next play Venus Williams or Alize Cornet in the third round as she bids for a fifth grand slam and second at Melbourne Park.
Australia's Samantha Stosur blew a 5-2 lead in the final set to continue her dismal run in her home grand slam, losing 6-4 1-6 7-5 to China's Zheng Jie.
Stosur, US Open champion in 2011, was serving for the match before her nerves seemed to get the better of her, allowing Zheng to claw her way back and reel off five games to clinch a place in the third round against Julia Goerges.