The glamorous Russian, on the comeback trail from a shoulder injury that forced her off the tour in August, battled past the tough American 6-3, 6-4 but her game was marred by too many errors and a serve that failed to fire.
"After (missing) my last Grand Slam in New York I have been so looking forward to this one and I was really happy to start," she said.
"She was a tough opponent and I'm just happy to get through the first one.
"I have had trouble against her in the past and I knew it would be no different tonight."
The four-time Grand Slam winner, in a powder blue dress, only made her return at the Brisbane International this month where she lost to bitter rival and eventual champion Serena Williams in the semi-finals.
Sharapova, who was using an ice vest even at 11:00 pm after a scorching hot day, won't be relishing a possible final meeting with Williams, who has a 15-2 record in their career meetings.
Now working with coach Sven Groeneveld after a failed, one-tournament partnership with Jimmy Connors, Sharapova comfortably held her serve then scored an early break when Mattek-Sands pushed a forehand long.
She was playing aggressive tennis and forcing errors from the American, which cost her dearly with the third seed racing to a 4-0 lead.
But the colourful Mattek-Sands, sporting purple dyed hair and her trademark knee socks, forced her way back into the game when Sharapova drove a forehand long to give her a glimmer of hope.
She held serve to go 4-2 and nearly got back to 4-3 with the Russian struggling with her service game, but failed to make the most of her opportunities with Sharapova closing out an error-riddled set in 48 minutes.
Sharapova got the break she was looking for in the third game of the second set, striking a powerful forehand down the line.
She held for 3-1 but the gritty American bounced back and squared the set at 3-3 as Sharapova's lacklustre serve again let her down with barely 50 percent of her first serves good.
But the end was in sight with the Russian breaking again in the ninth game and serving out for a match in which she made 28 unforced errors and converted only half of her eight break points.
Mattek-Sands, ranked 41, has now exited in the first round all three times she has played Australian Open.
Sharapova, who won the Australian Open in 2008 and made the final in 2007 and 2012, next plays Italy's Karin Knapp as she looks to go one better than last year, when lost to Li Na in the semi-finals.