The song received positive reviews from contemporary music critics, with many praising its sound similar to JoJo's second mixtape Agápē (2012).

The song's accompanying music video was shot in director Zelda Williams' front yard while in quarantine due to the COVID-19 pandemic against a white bed sheet backdrop.

[2] During a live stream interview with Entertainment Weekly JoJo stated that the single released version of the song would include a male feature.

[5][6] JoJo said the song "continues on the journey of self love that I've been on... how temptation and doubt arise... but at the end of the day how choosing self preservation over toxic relationships is the vibe right now".

[4][7] JoJo camped out at House of Balloons in Toronto, Canada with songwriters Lowell and Doc McKinney during early writing sessions for the song.

[8] "Lonely Hearts" was written by Elizabeth Lowell Boland, Martin McKinney, Merna Bishouty, Dylan Wiggins and JoJo for her fourth studio album Good to Know (2020).

[11] "Lonely Hearts" received positive reviews from contemporary music critics, with many praising its honed R&B and hip hop infused sound alongside its confessional commentary.

Ykigs from YouKnowIGotSoul praised the urban direction the song takes, stating "The smooth R&B record is what many have been wanting from JoJo for years and she delivers here".

[12] In a track-by-track album review, Jonathan Currinn from CelebMix said the song is "undeniably powerful" and "easily showcases JoJo's versatility especially when we expect her to come out with incredible runs and beautiful vocals, and she does exactly that with calm precision that have a yearning quality to them".

[18] It was inspired by photographer Herb Ritts who was known for his take on black and white nude photography, while also channeling 1993 sports illustrated model Kathy Ireland.