Hip surgery has hampered the Australian's form this season, making early exits in Rome, Madrid, Nice and at the French Open.
But the 21-year-old did just enough to get himself over the line in the ATP 250 grass-court event at Queen's Club, beating Tim Smyczek 6-4 3-6 7-5 - his first main-draw triumph since January.
Tomic looked set to be heading for another premature departure when his serve was broken late in the third, but won three games on the bounce to book himself a place in the second round.
Compatriot and four-time winner Lleyton Hewitt eased into the next stage with a 6-3 6-3 triumph over Daniel Gimeno-Traver.
The former world number one was in impressive form as he disposed of his opponent in just over an hour, winning each of his service games.
Jeremy Chardy became the first high-profile exit as the number 14 seed was dumped out by the United States' Sam Querrey 7-6 (7-4) 6-7 (4-7) 6-7 (5-7).
Querrey will now meet fellow American Denis Kudla, who got the better of Michael Russell on Monday.
The home pairing of Dan Evans and James Ward gave local spectators cause for celebration as they both pulled off first-round upsets.
Ward will meet Grigor Dimitrov after beating Blaz Rola 7-5 6-4, while Evans battled to a 6-3 6-7 (5-7) 7-6 (7-2) victory over Jurgen Melzer - ranked 88 places higher - to set up a second-round clash with Kevin Anderson.
Paul-Henri Mathieu can expect to play in front of a bumper crowd later this week after beating Aljaz Bedene to book his place against reigning champion Andy Murray in the next round.
There were also wins for James Duckworth, Nicolas Mahut, Adrian Mannarino, Kenny De Schepper and Sergiy Stakhovsky at the expense of Dudi Sela, Marsel Ilhan, Daniel Cox, Somdev Devvarman and Daniel Brands respectively.
The final match of the day, between Dusan Lajovic and Feliciano Lopez, was suspended due to rain, with the latter a set up. The encounter will reach a conclusion on Tuesday.