The clear moral of this excellent story is the danger of being overwhelmed by flattery. The fox of course shows himself to be a master of flattery and is able to use this strategy to snatch Chanticleer away. Of course, Chanticleer, once he has escaped, himself takes this lesson to heart:
"You'll not, with your soft soap and flatteries
Get me to sing again, and close my eyes!"
However, at the same time, there seems to be a moral in the way that Chanticleer is able to turn the tables on the fox by using flattery to secure his release. By pretending that the fox is so worthy and mighty, he uses exactly the same strategy that was used against him to rob the fox of his dinner. Thus a second moral could be said to be that our greatest weakness can also be our greatest weapon.
Lastly, it is important to remember that Chanticleer only goes out into the yard to strut and preen at the behest of his beloved Pertelote, who berates him into ignoring the warning he has been given. As such, Chanticleer is shown to be a victim of love. If it were not for Pertelote, he would never have been seized by the fox. Therefore, another moral seems to be that men need to be wary of paying attention to the advice of women. Let us remember that in Chaucer's time women were traditionally portrayed as being the temptress figure and responsible for man's Fall from the Garden of Eden.