The Sliding Doors star is renting an apartment near her mother Blythe Danner while she films new movie Iron Man 2.
But she was horrified when her advisers discovered vermin had taken up residence at the plush home, according to Britain's Daily Mirror newspaper.
And the actress was forced to hire an expensive rat catcher to rid the property of the unwanted guests.
A friend tells the publication, "Gwyneth wanted everything to be perfect. She was so excited about moving to L.A. with the family and to be closer to her actress mum. It will be the first time in ages that she, Chris and the children will be living together as a family.
"But her stomach turned at the thought of rats running around. She didn't want her homecoming ruined by those horrible creatures. Being an animal lover, Gwyneth didn't want the vermin harmed, just removed."
The couple applied finishing touches to the summer home last week (begs06Apr09), where they will stay while Paltrow films action sequel Iron Man 2. Martin will take care of their children - Apple, four, and Moses, three - when he returns from the first leg of a world tour with his band Coldplay.