FBI agent, Malcolm Turner (Martin Lawrence), reprises his disguise as an old lady to become a nanny in order to expose Tom Fuller (Mark Moses), the suspected designer of a deadly computer "worm". Malcolm must once again rely on his sure-fire alter ego, the take-no-prisoners Hattie Mae Pierce, a.k.a. "Big Momma," to bring down the bad guys and prove that a woman's work is never done!
Undercover Agent Malcolm Turner ( Martin Lawrence) is back and this time he's out to expose the suspected designer of a deadly computer "worm" that would allow outside forces access to sophistical and critical government intelligence files. But unfortunately, the only way the crafty agent can get next to the worm's creator, Tom Fuller (Mark Moses), is to access the programmer's Orange County home as the new "nanny" to Fuller and his wife Leah's (Emily Protor) children: toddler Andrew and his two older sisters, Carrie (Chloë Grace Moretz) and Molly (Kat Dennings). This means that Malcolm must once again rely on his sure-fire alter ego, the take-no-prisoners Hattie Mae Pierce, a.k.a. "Big Momma," to bring down the bad guys and prove that a woman's work is never done!