"She's young, she's letting everyone know she's growing up," Timberlake said about the former "Hannah Montana" star on radio's WWFS-FM, New York, Tuesday.
"It was the VMAs, what did you guys expect? It's not like she did it at the Grammys. Let her do her thing," Timberlake said.
"Madonna, wedding suit," he added. "Britney [Spears], strip tease."
Cyrus, 20, was seen scantily clad, grinding against singer Robin Thicke and making vulgar gestures with a foam finger throughout her performance at the VMAs Sunday night.
Timberlake, 32, is also a former Disney star who has been the focus of controversy.
The "Mickey Mouse Club" veteran sparked a media firestorm in February 2004 when he tore off part of Janet Jackson's black leather costume and revealed her breast while they were performing the halftime show of the Super Bowl XXXVIII, broadcast on CBS.