At the critical moment, Anakin disarms Mace by slicing his arm off with his lightsaber, and Sidious strikes Windu with Force lightning. A stunned and weakened Windu is thrown out of the window, supposedly falling to his demise.

Did Mace Windu really die?

Windu bested Palpatine in the confrontation and—deciding the chancellor was too dangerous to be left alive due to his influence over the government—prepared to strike him down, but the intervention of Anakin Skywalker, who saved the chancellor's life, led to Windu's death.

Was Mace Windu's body found?

One is that his body was discovered and unceremoniously disposed of. After all, in the wake of Order 66, it's unlikely they'd be holding ceremonies to honor dead Jedi. The other is that he landed in such a place that they never actually found his body.