Diaz grew up in Lancaster County, Pennsylvania, where she was home-schooled by her Peruvian mother, Nancy, a proponent of early childhood development and the visual arts, and her Danish father, Eric, a woodworker and musician.

The two began their collaboration when a fellow student, a producer looking for a project, offered Diaz the chance to record an album in Hawaii.

[11] The song "The End of the Day", written by Diaz and Sarah Siskind, was featured on the television series Nashville, and is performed by Connie Britton and Charles Esten.

On February 11, 2021, Anti- Records announced that Diaz had signed with them, alongside the release of her first single with the label titled "Man in Me".

[12][13] In early 2023, Madi Diaz joined Harry Styles's band playing guitar and singing backup vocals for the European leg of Love On Tour.

In Spring 2024, Diaz supported her friend Kacey Musgraves on the UK and European legs of her Deeper Well World Tour.