She will debut as the elder sister of Will Gardner (Josh Charles) in a forthcoming episode, according to TVLine.
Her character Sara and younger sibling Audra - played by Nurse Jackie's Merritt Wever - will pay Will a visit, determined to find their brother a woman.
"Like every single man with sisters, they are obsessed with finding him a wife," explained series co-creator Michelle King.
Dajani recently featured in three episodes of USA's Necessary Roughness and has also appeared on Body of Proof, Ugly Betty and Curb Your Enthusiasm.
Parker Posey, Denis O'Hare and Amy Sedaris will all reprise their Good Wife roles in an upcoming episode, due to air in February.
Glee's Jonathan Groff will also appear in the instalment, playing a young man who sues a software company after his sister disappears in Syria.
The Good Wife airs on Sundays at 9/8c on CBS in the US. More4 airs the show on Thursdays at 9pm in the UK.
> Rita Wilson plans The Good Wife return
Watch a promo for the next episode of The Good Wife below: