The phrase "action on her behalf" is correct and usable in written English.
It can be used when referring to steps taken or decisions made for someone else, typically in a legal, formal, or supportive context.
Example: "The lawyer took action on her behalf to ensure her rights were protected during the proceedings."
Alternatives: "action for her" or "steps taken for her".
Frustrated and infuriated by his lack of action on her behalf and his cruelty towards her, and in the grip of a paranoia which developed into schizophrenia, she shot him in 1968 (not fatally) and gained brief fame.
Amnesty put out an Urgent Action on her behalf which led to her release from prison.
I sprang to action on her behalf, stopping at a St. Paul Goodwill store, with less than 10 minutes to browse.
One clever piggybacking action on her behalf, covered by Los Angeles Times' David Ng, is the joke circulating on Twitter: "a fake playbill notice for the Broadway musical 'If/Then' states that its star, Idina Menzel, will be replaced by her alter-ego, Adele Dazeem".
In a civil rights action filed on her behalf by the Connecticut Fair Housing Center, the judge awarded Ms. Parris nearly $350,000 in damages and lawyers' fees, the largest judgment in the center's history.
A reporter for The New York Times tells of a 26-year case involving an abused runaway and the class-action lawsuit filed on her behalf that sought to make New York City's foster care system fairer for all its children.
Her outbursts were evidently also capable of frightening her younger daughters and after Lady Grange's kidnapping, no action was ever taken on her behalf by any of her children, the eldest of whom would have been in their early twenties when she was abducted.
Her first action on his behalf was to advise his concerned parents not to try to prevent him from pursuing a career on the stage.
It's time for the medical community to demand action on patients' behalf.
