[3] From the late 1970s to 1990s he also played for Dundee, Heart of Midlothian, Charlton Athletic, Bristol City, Airdrieonians, Portadown and Dundalk.
Ferguson started his professional career with Dundee, who signed him from Fir Park Boys Club in 1978.
[3] Ferguson stayed behind after training with manager Tommy Gemmell and his assistant Willie Wallace, both Lisbon Lions, to hit shots at Scotland international squad goalkeeper Ally Donaldson.
He scored the only goal with a low right foot shot from 12 yards in the 1984 Scottish League Cup Final (October) against Dundee United.
A few days later he scored two goals in a 3-1 UEFA Cup win against Internazionale of Milan (Rangers lost 4–3 on aggregate).
[8] He headed the winner in the 2–1 defeat of Barcelona at the Camp Nou and the opening goal in the semi-final victory at Borussia Mönchengladbach.
He scored his team's first two goals in the 3-2 Scottish Cup semi-final win over his ex Dundee side at neutral Tynecastle Park.
Television commentator Archie MacPherson said in response, "Somebody once said to me about Iain Ferguson, he doesn't score ordinary goals, they are all smashers.
"[4] In the 1987 Scottish Cup Final Ferguson had an extra time goal disallowed much disputed by him and his teammates.
[3] Terry Butcher in the television punditry after initially sitting on the fence regarding the offside decision then said he felt the goal should have stood.
He scored another important goal notching the only strike when Hearts defeated Bayern Munich in the first leg of 1988–89 UEFA Cup quarter finals.
He latched on to a free-kick tapped to him by Tosh McKinlay to hit a 25-yard drive past Raimond Aumann into the net[3] described by television commentator Jock Brown as "a shot of stunning power from Iain Ferguson".
Robertson returned to Tynecastle only 8 months after his departure meaning Ferguson was largely demoted to the substitutes' bench.