His contract with Nancy expired in June 1979, and Internazionale, Paris Saint-Germain, and Saint-Étienne emerged as the clubs most likely to sign him, although the Nancy club president had been unwilling to let Platini leave. Having set his mind on a transfer to Saint-Étienne, he signed a three-year contract with les Verts.

Platini's three years at Saint-Étienne were a mixed success. The club had signed him with a view to success in the European Cup, but despite some excellent results (including a 6–0 win over PSV in the 1979–80 UEFA Cup and a 5–0 win at Hamburger SV in the UEFA Cup the following season), the club were unable to surpass the feats of the Saint-Étienne side that had reached the final of the 1976 European Cup.

Platini won the French league title in 1981 with Les Verts, but was on a losing Saint-Étienne side in two French Cup finals, against Bastia in 1981 and against Paris Saint-Germain in 1982, in what was his last match for the club before joining Juventus. He left for a nominal transfer fee and would go on to be European player of the year 3 times with the Italian side.

Association Sportive de Saint-Étienne Loire is, arguably, the most successful club in French football history having won ten Ligue 1 titles, six Coupe de France titles, and five Trophée des champions.

Blooded at Ajax, Johnny Rep played with Cruyff, Keizer, Krol, Haan and Neeskens and won two League titles, two European cups and a World club cup before moving to Valencia in 1975. He finished a runner-up in two World cup finals and remains Hollands top scorer in the finals.  Rep joined Saint-Étienne after a short spell at Bastia. The talismanic dutchman earned his nickname 'Goudhaantje (Goldcrest)' due to his ability to score decisive goals. He scored 44 in 131 appearances and won the French title with Michel Platini in 1981.

In 1976, Saint-Étienne became the first French club since Reims in 1959 to reach the final of the European Cup. Played at Hampden Park in Scotland, they faced two time defending champions Bayern Munich. The match was hotly contested with Les Verts failing to convert numerous chances.

A single goal by Franz Roth eventually decided the outcome and Saint-Étienne supporters departed Scotland in tears; however, not without nicknaming the goalposts "les poteaux carrés" (the square posts). Saint-Étienne did earn a consolation prize by winning the French league to cap off a successful season but, despite being a contender abroad for many years to come, they never again got close to Europe's biggest prize.