Vunipola faced a suspension if found guilty but the decision means he is instead free to face Clermont Auvergne in Saturday’s European Rugby Champions Cup semi-final.
The 22-year-old pleaded not guilty to the charge, which the club argued was an innocent collision. The Rugby Football Union’s three-man disciplinary commission also rejected the suggestion that he was guilty of the lesser crime of charging into a ruck.
Saracens have already won one trophy in the LV= Cup and are on target to reach the Premiership play-offs. They reached the final of Europe’s top club competition last year, only to lose to Toulon, but progressed to the last four again with a hard-fought quarter-final win over Racing Metro.
The north London outfit have Jacques Burger back in contention for the trip to Saint-Etienne. The Namibia flanker received a one-week ban last week after admitting striking Racing scrum-half Maxime Machenaud.