Nancy O'Dell has some big pumps to fill.

O'Dell will take over as co-anchor of Entertainment Tonight when Mary Hart leaves the show next year, RadarOnline.com can report.

O'Dell - formerly of rival Access Hollywood - will join ET as a special correspondent and substitute co-anchor beginning in January 2011 and will assume the role of co-anchor, after Hart ends her final season on the show next fall. Mark Steines will remain as co-anchor of the program.