When midfielder Ian McDonald arrived at Firhill from Eastercraigs BC as a raw 16 year old at the start of the 1975-76 season he began an almost unbroken 14-year association with Partick Thistle. Not surprisingly for a young player, McDonald didn't go straight into the first team upon his arrival at Firhill. His first season at Partick was spent exclusively in the reserve team where he quickly earned a reputation as a clever and versatile (he played a number of games as centre forward) player. He was among the most talented players of his age group and that ability was recognised when he was selected to play for a Home Scots XI against an Anglo Scottish XI at Love Street. He also accompanied a Scotland Youth team to the Festival of Youth at Cannes although an out of date passport nearly meant that the young McDonald had to stay behind in Scotland.

A breakthrough into the Thistle first team came at the start of the 1976-77 season when he appeared as a second half substitute in Thistle's very first Premier Division fixture against Ayr United. That though would he one of just three substitute appearances that McDonald would make that season, his football education continuing with the Thistle Second XI. Hopes that Seasom 1977-78 might mark a significant breakthrough into the first team squad were dashed when a knee injury required surgery, Not until March of that season would McDonald return to action. The competitive nature of the Premier Division was such that it wasn’t always considered the right environment to introduce youth talent and although now full fit McDonald was again restricted to only a handful of substitute appearances in 1978-79 season. That, however, was soon to change, for in the second half of the 1979-80 season, the name Ian McDonald started to appear on a Thistle team sheet on a regular basis.

His long awaited first start came against Hibs in December 1979 and that had been preceded some weeks earlier when he came off the bench to score his first goal against Aberdeen. Of the last eleven games of that season McDonald played in ten of them. From now on till McDonald’s departure from Firhill in May 1989 he was in the side far more often than he was out of it. It wasn’t the happiest of eras for Thistle though. The club survived another Premier Division season with McDonald playing 32 times in 1980-81 but relegation would follow 12 months later. Although twice Thistle would come close to returning to the Premier Division. In season 1982-83 McDonald would play 47 times and score three goals, including a vital late strike in a League Cup-tie at Brechin City, but Thistle could manage no better than fourth in the First Division. When Thistle’s next promotion challenge ended in failure McDonald’s Thistle career looked to be over.

In the summer of 1984 he moved to Motherwell but spent just a few months at Fir Park and by December he was back in the fold at Firhill. Jamie Doyle moved to Motherwell, coming to Firhill in exchange for him were McDonald and Gregor Stevens. McDonald’s debut second time around came against the same side, Ayr United, against whom he had made his initial Thistle appearance, back in September 1976. Seven days earlier, Thistle had lost 7-3 at home to St Johnstone, but with McDonald back in the side Thistle defeated Ayr 2-0. The remainder of that season and also the next few would present real struggles. McDonald, was a midfielder more of the creative nature rather than a ball winner often bore, unfairly, the brunt of the Thistle fans' frustrations despite making quite often telling contributions.

In season 1986-87 Thistle made a quite miserable start of the season and not until the eleventh game when McDonald scored the winner against Brechin City, did they record a victory. In the next campaign McDonald added goalscoring to his repertoire and scored nine goals including a run of four in six games across October and November. Season 1988-89 would be his last as a Partick Thistle player. He had a spell on loan at Stranraer and although he appeared as a substitute in John Lambie’s first match as Thistle manager, he would make only a further five appearances, the last of which came on the last day of the League season against Raith Rovers. McDonald started the next season at Morton and after a number of seasons in their midfield he joined the club’s coaching staff.