The Russian had only played once since pulling out of Wimbledon last summer with a shoulder injury but she produced a fearsome all-round performance on Monday in Australia.
Garcia did not play badly she was given a lesson in consistency with tournament third seed Sharapova dominant, especially on serve.
Sharapova went through 6-3 6-0 in 64 minutes and will pose a serious threat on this form to the title aspirations of the top two seeds, Serena Williams and Victoria Azarenka.
She was joined by number five seed Angelique Kerber, who eased through in straight sets against Kristina Mladenovic.
The world number nine from Germany was better on all counts and took just 73 minutes to wrap up a 6-2 6-2 victory.
World number eight Jelena Jankovic resisted a second-set fightback by Francesca Schiavone to move into the second round.
Neither woman was particuarly potent with their serve but fourth seed Jankovic was more solid all round and triumphed in the tie-break for a 6-2 7-6 (8/6) victory.
Ninth seed Dominika Cibulkova enjoyed a 6-4 6-3 victory over Britain's Heather Watson.
World number 17 Carla Suarez Navarro eased through with a 6-2 6-1 victory over Hsieh Su-Wei in just 58 minutes.
The Spaniard will now meet Kaia Kanepi after the Estonian resisted a fierce challenge from qualifier Alexandra Panova.
Kanepi, the world number 30, will have to be more consistent though after 11 aces were counter-balanced by seven double-faults as she claimed a 6-3 6-7 (8/10) 6-2 victory in a little over two hours.
However, there was a shock when world number 33 Daniela Hantuchova went down to a 6-3 7-5 defeat to Ashleigh Barty.
Barty made a nonsense of the rankings gap of 154 places as she produced a better all-round game to win in one hour 20 minutes.
In the men's draw, seventh seed Dmitry Tursunov failed to clear the first hurdle, losing in straight sets to American Sam Querrey.
The Russian world number 29 had no answer to his opponent who dominated on serve with 18 aces and winning 90 per cent of points on his serve.
Fifth seed Grigor Dimitrov had no such problems as he eased to a 6-2 6-3 victory over Robin Haase.
Marinko Matosevic made up a rankings deficit of 26 places to edge out Julien Benneteau 5-7 6-4 7-6 (7/4).
World number 39 Jarkko Nieminen eased through against an inconsistent James Duckworth 6-2 6-3.
Marin Cilic edged out Denis Istomin after a close three-set match.
Istomin took the first set on a tie-break before his opponent hit back to seal a 6-7 (3/7) 7-6 (7/5) 6-4 victory.