With Paris Saint Germain he won one Ligue 1 in 1994, placed second in 1993, 1996 and 1997, won the Coupe de France twice, in 1993 and 1995, won one Coupe de la Ligue in 1995, and one Cup Winners' Cup in 1996. He was also a finalist in the Cup Winners' Cup in 1997, and won another Coupe de France in 1990 with Montpellier.
With France he won the UEFA Under 21 European Cup in 1988 (13 matches played), and earned 19 full international caps, scoring 2 goals, as well as participating at Euro 1996.
In 1997, the French Football Federation moved to suspend Guérin after he failed a drugs test administered after a PSG game on 5 October. Guérin appealed unsuccessfully to the FFF's doping appeals commission, who awarded him an 18-month ban, 12 months of which were suspended. Guérin subsequently appealed to the French federal Administrative Court at Versaille, contesting the FFF's decision on several counts. The court at Versaille upheld one of Guérin's contentions, that the drugs test was improperly administered, and thus decreed that the entire process should be deemed void. Resultantly, the FFF-imposed suspension was annulled.