[1] Knowing each other from film school in Savannah,[4] Muller and Matthews started the project Teen Dreamz in 2013, which acted as a precursor to Boy Harsher.

[9][10][11][12] Boy Harsher is often labeled as a dark wave group,[2][13] with influences ranging from early forms of industrial to electronic body music.

He has characterized Boy Harsher's music by its minimal beats and synth textures, as well as by Matthews's dynamic vocals that depict "desire, fantasy, and loneliness.

"[16] Michael Lawson of The Skinny thought that the band "straddled the middle ground between melancholic cold wave and regimented synth workouts.

"[3] Boy Harsher draws heavily from cinema, theatrics and graphic design to tailor the band's visual imagery;[2][14][17] Matthews and Muller both have a background in filmmaking.

[17] Matthews has expressed appreciation for various female vocalists, including Nico, Circuit des Yeux, Alison Lewis of Linea Aspera, Chelsea Wolfe and Zola Jesus, whereas Muller named Sleep Chamber, Suicide, DAF and Yello as early musical influences on Boy Harsher.

"[17] A "half-functioning" Roland Juno-106 was used extensively on the Lesser Man EP; their live set features synth lines sampled into an Akai MPC, as well as backing tracks.