It was a dominant performance in which he made quick work of Lesnar, landing strikes at will from the opening bell and finishing it off with a kick to the liver, followed by punches.
Overeem's performance tonight confirmed that he deserves to be talked about as one of the best heavyweights on the planet, but the fight didn't answer all of the questions we have about Alistair.
Here's five questions we still have about Alistair Overeem:
Can he a stuff the takedowns of a high-level wrestler?
Yes, Overeem stopped one takedown from Lesnar, but it was a halfhearted single leg.
For whatever reason, we didn't see Brock explode forward and try to double leg Overeem and so we still don't know how 'Reem would react to that.
It will likely be a while before we see this question answered, as there are not a lot of elite wrestlers at the top of the heavyweight division.
Can he take a punch?
Since moving to the heavyweight division, we have not seen anyone test Overeem's chin.
When he was fighting at light heavyweight, we saw him knocked out on multiple occasions, however.
It's rare that someone's chin gets better over time, but it's still curious to see how good a punch Overeem can take and how would react to getting tagged with a big shot.
Has his cardio improved?
Though cardio seems a useless commodity in the heavyweight division these days, what with so many of the fights ending early, it would still be interesting to see where Overeem's cardio is at.
In his fight with Fabricio Werdum earlier this year, Overeem's cardio looked sub par, as he was noticeable winded in a fight that was far from grueling.
Whether or not he'll ever need his cardio remains to be seen, but with fighters like Cain Velasquez looming in the background, it is a possibility.
Is his striking as good as it's made out to be?
There's no doubt that Overeem is a fantastic striker, but is he as good as people say?
Since moving to the heavyweight division, we have not seen Overeem face off against an elite MMA striker.
He has done very well against kick-boxers in K-1, but striking in an MMA fight is different because there are so many more factors to be conscious of.
For instance, when Overeem fought Werdum, he was worried about the fight going to the ground and it showed, as Werdum was able to land solid punches on several occasions.
It will be interesting to see how Overeem fairs against a fellow elite striker, UFC heavyweight champ Junior Dos Santos, later this year.