Jerry "Wonda" Duplessis produced the song and co-wrote it with de Lesseps, Arden Altino, Angela Ann Hunte, Tzvetin T. Todorov, and Urales Vargas.

She premiered the song during an episode of Watch What Happens Live with Andy Cohen, and its lyrics partially reference an argument between de Lesseps and American author Carole Radziwill that occurred while vacationing in the Turks and Caicos Islands.

[1] Dave Quinn and Jessica Fecteau, writers from People, both noted the song's girl power theme, with the former calling it funky.

[2] While vacationing with the Real Housewives cast in the Turks and Caicos Islands, she took issue with some members, specifically author Carole Radziwill, for entering a relationship with the former boyfriend of de Lesseps' niece.

[11] In the chorus, "I'm just doing me / You broke the girl code / So don't be so uncool / I gotta let you go", Ben Rimalower from Vulture felt she expresses her want of "support and company" from her friendships.

[1] Bustle's Kristie Rohwedder ranked de Lesseps' first three singles, and provided the lowest score to "Girl Code"; however, she enjoyed its lyrics, danceability, and catchiness.

[16] Retrospectively, Sadie Gennis from TV Guide Magazine listed "Girl Code" as the tenth best Real Housewives song in a 2017 article.