"Starting the year in this way is very, very positive," said del Potro.
"I'm looking forward for the rest of the season. I need to still work in the same conditions and the same way. Now starts the hardest tournament for us, and I will see if I can go farther than last year in Melbourne."
Del Potro has won five tournaments in a row as the top seed, following victories at Basel (2013), Tokyo (2013), Washington (2013) and Vienna (2012). He received $82,040 and 250 ATP Ranking points while runner-up Tomic earned $43,210 and 150 ranking points.
The 25-year-old del Potro is the first Argentine to win the Sydney title since David Nalbandian triumphed in 2009. He improved to an 18-7 finals record; last year he lifted four trophies.
Del Potro improved to a 2-0 head-to-head record over Tomic as he lost just six points on serve in the 53-minute match. The Tandil native broke Tomic four times and hit eight aces. He was presented with the trophy by Ken Rosewell, after whom the centre court is named in Sydney.
"The finals never are easy, but I was surprised of my level tonight," del Potro was quoted as saying by atpworldtour.com. "I think I played great. My forehand worked perfectly; I made a lot winners, many aces; I played good slices.
"I think Bernard was a little frustrated after seeing me very focused on the match and hitting the ball so well. He is still young in some moments of the match, but he has everything to win titles and he will reach finals very, very soon."
The 21-year-old Tomic was looking to retain the title he won with victory over Kevin Anderson last year. The Australian had powered through the draw unseeded and now goes on to face World No. 1 Rafael Nadal in the first round of the Australian Open.