Gillmeister's first-grade debut in the Brisbane Rugby League premiership came in Round 5 of the 1983 season for Northern Suburbs at nineteen years of age.

In 1993, Gillmeister again helped the Broncos to a 14-6 grand final win against their same opponents from the previous year's decider, the St. George Dragons.

Prior to the 1993 grand final victory, the Broncos announced that they could not re-sign Gillmeister due to salary cap restrictions, prompting him to move on to the Penrith Panthers after playing 72 games for Brisbane and scoring eight tries for a total of 32 points.

To start the 1995 ARL season, Gillmeister had the honour of scoring the club's first-ever try in its season-opening 24–6 loss at Suncorp Stadium against the Canberra Raiders.

At State of Origin level, Gillmeister defied his stature by continually hurting the Blues' forwards with stinging defence throughout his career.

In 1995, after nearly ten years in the New South Wales Rugby League, including two grand final victories with the Broncos, and 21 State of Origin games for Queensland, Gillmeister made his Australian debut when he was selected as a reserve forward for the first Trans-Tasman Test match against New Zealand at Suncorp Stadium.

Despite good performances throughout the remainder of the 1995 season, Gillmeister missed out on a place in Australia's World Cup winning team at the end of the year, leaving his three Tests against New Zealand as the only time he was selected to represent his country.

In 2006 it was announced that he had been signed as an assistant coach by the newly formed Gold Coast Titans, who were to enter the NRL competition at the start of the 2007 season.

[6] Following the death of his father Ron from mesothelioma in 2009, which he contracted while working in Gladstone in the 1970s, Gillmeister became an ambassador for the Asbestos Related Disease Support Society Queensland.