Normally, lions do not eat other lions but it is reported anecdotally that there have been exceedingly rare exceptions of male lions eating the young offspring of females in a pride that they wish to take over. Perhaps the biggest exception is the legend of the Mapogo lions who were notorious for killing a large number of male and female adult lions and their cubs in their apparent desire for dominion over other lions living in an area called the Sabi Sands which is now a game reserve.
A coalition of male lions may take over a pride and in doing so they not infrequently kill the cubs in order to stimulate oestrus in the females so that they can mate with them and create their own cubs; their dynasty. But they don’t eat the cubs they’ve killed. They just want to kill them for the purpose stated.
Lions also can be scavengers when prey is scarce. Lions are sometimes killed by the prey that they attack. Therefore, it would seem feasible to suggest that sometimes, under dire circumstances, a lion may scavenge on the carcass of another lion which means that sometimes lions eat other lions through scavenging.
But to return to the Mapogo lions which were an anomaly. They appear to have operated as a gang of six during 2006-2012, patrolling their territory and killing competitors and sometimes eating lions to stamp their authority over their domain.
One website, Africa Geographic states that whole prides were wiped out by this murderous gang in their desire for dominance over challengers. The author states that a lion eating another lion is “almost unheard of”. That’s the point I’ve made in the opening paragraph.
The Mapogo lions killed over a hundred lions it is reported or speculated. The true number is not known.
There are also, apparently, documented cases of incoming males to a pride killing cubs that aren’t their own and eating the bodies but this must be an exception.
The default character of lions is that they are not cannibalistic. It is notable that my excellent book on the wild cat species, Wild Cats of the World, makes no mention of cannibalism by African or Asian lions. The book is very well researched, relying on copious amounts of references by many scholars. The authors of the book, Mel and Fiona Sunquist, did not see fit to mention cannibalism among lions and therefore they never bumped into this aspect of their behaviour in the research papers that they depended upon. This points to the rarity of lions eating other lions.
It would appear that the information about cannibalistic lions is almost always anecdotal and may not be totally reliable. What I mean is that you can read about this on the Internet in articles written by non-scholars which is then repeated by others. Also, the Mapogo lions are said to be legendary and legends are not necessarily factual. And if there is any fact backing up the Mapogo lions’ behaviour it is an anomaly and it is very rare for a lion to consume another adult lion. But apparently it can happen and therefore the answer to the question the title is yes, sometimes but extremely rarely.
Perhaps a critical factor is the availability of prey and the dire circumstances under which the lions can find themselves. Desperate acts of survival will result in desperate behaviours which will be, by definition, rare.
Below are some more articles on lions.