Jenny McCarthy I SUPPORT Jim Carrey's Daughter on 'American Idol'

2/6/2012 8:00 AM PST

Jim Carrey's "American Idol" wannabe daughter is getting support from an unusual place ... her father's ex-girlfriend.

Jenny McCarthy ... who dated Jim for 5 years before splitting in 2010 ... was out in L.A. this weekend, when we asked if she will back Jane on "Idol."

Without hesitation, Jenny declared ... "YES."

24-year-old Jane got a golden ticket to Hollywood this season after busting out a version of "Something to Talk About."

As for Jenny and Jim ... they had a pretty weird breakup ... with Jenny telling Oprah the relationship had stopped being fun ... and Jim tweeting, "I am now free 2 be my whole self."