A member of the public complained to the Portman Group, the industry watchdog, about the two-litre bottle of Asda's own-label cider, which has an alcoholic strength of 5.3%.
The complaint said the word "strong", printed in bold capital letters across the label, "glamorised" the product's alcoholic strength.
The Portman Group's independent complaints panel ruled the packaging made alcoholic strength its dominant theme, and therefore found it in breach of the code on the naming, packaging and promotion of alcoholic drinks.
David Poley, chief executive of the Portman Group, said: "Drinks companies must not market their products on the basis of their alcoholic strength and the Portman Group Code makes this very clear. We welcome that Asda has acknowledged the problem and taken rapid action to change its labelling."
Asda was unavailable for comment.