Wiig would play a love interest to Steve Carell's dim-witted weatherman Brick Tamland in the sequel, according to The Wrap.
Paul Rudd, Christina Applegate and David Koechner will also reprise their roles from the 2004 original. The cult comedy, about a chauvinistic news anchor in 1970s San Diego who is forced to adapt to changing times, grossed some $85 million at the domestic box office.
The sequel's script is still being written, but the film will likely start shooting sometime in the first quarter of 2013. Adam McKay is again directing, with the prolific Judd Apatow ("This is Forty") producing.
"SNL" vet Wiig starred in last year's smash comedy hit "Bridesmaids," which was also produced by Apatow.
She'll soon be seen in Errol Morris' "Freezing People is Easy" (also starring Rudd), and the remake of "The Secret Life of Walter Mitty," starring Ben Stiller
“Anchorman: The Legend Continues" is tentatively scheduled to be released in October 2013.