[14] During her first year, Moss co-directed the Cambridge Amateur Dramatic Club production of Road at the ADC Theatre,[14][15] which led to her first meeting with Toby Marlow, who was in the audience.

[14][16] That year, she also appeared as a dancer in a Cambridge University Amateur Dramatic Club production of the musical Rent, which featured Marlow and Zak Ghazi-Torbati in leading roles.

[1] Marlow came up with the idea of a pop concert featuring the wives of Henry VIII and asked Moss to help write it, after being offered a slot at the Edinburgh Festival Fringe by the Cambridge University Musical Theatre Society.

"[13] As she later told The New York Times, after watching the BBC documentary series Six Wives with Lucy Worsley, Moss realised, "'Ooh, I think this could be cool, as a feminist thing.

[13] On their first day of writing, Moss and Marlow watched Beyoncé's 2011 video album, Live at Roseland: Elements of 4, which provided inspiration on how to weave storytelling into a concert performance.

[1][14] Rating it a "'must see' show of outstanding quality", FringeReview said that "whoever came up with the choreography deserves a large round of applause too as it was different for each number, appropriate to the mood and the music and faultlessly executed.

[1] Following additional performances at Cambridge, Moss and Marlow received financial backing from a team including George Stiles, Kenny Wax, and Wendy and Andy Barnes.

[4] In August 2019, Lucy Moss and Toby Marlow signed a deal with Warner Chappell Music to take the songs from Six to "even more fans worldwide".

[30] In December 2020, Lucy Moss directed Ratatouille: The TikTok Musical, which was pre-filmed and streamed as a virtual performance while most theaters remained closed during the COVID-19 pandemic.

[32] According to producer Greg Nobile, he and writers Michael Breslin and Patrick Foley quickly agreed on Moss as their first choice for director.

"[8] On 16 March 2022, Lucy Moss was announced as director of a new production of Legally Blonde at the Regent's Park Open Air Theatre in London.