The Girlfriend was filmed primarily in the United Kingdom and Spain. Key filming locations include high-end areas in London such as St. John’s Wood, St. Ermin's Hotel in Westminster, and Soho. Other UK locations include Syon House in Brentford, a quarry near Chepstow on the Welsh-English border, and Shepperton Studios in Surrey. In Spain, the filming took place in the Málaga province, including locations like Marbella, Ronda, and Villa Tramores in Benahavís, as well as natural sites like Cueva del Gato in Andalusia. These locations helped provide a mix of urban sophistication and scenic landscapes reflective of the show's themes.