Initially inspired by pop artists and her experiences with panic disorder, Trainor rewrote the album to adapt to changing trends in the music industry and the rising popularity of hip-hop.

It features guest appearances by Sabath, Nicki Minaj, Lennon Stella, Sasha Sloan, the Pussycat Dolls, and AJ Mitchell.

Treat Myself is a pop, doo-wop, funk, and R&B album with hip-hop influences which explores themes such as body image, self-esteem issues, and relationships.

Treat Myself includes three singles: "No Excuses" (2018) and "Nice to Meet Ya" (2020), which respectively peaked at numbers 46 and 89 on the US Billboard Hot 100, and "Wave" (2019).

Some reviewers thought the quality of Treat Myself was worth the wait and effectively showcased Trainor's artistic range, while others commented on its production choices and criticized its lyrical themes.

[7] Trainor was inspired to write the title track of Treat Myself when her therapist asked her to "reward" herself after surviving bouts of anxiety from her panic disorder.

In January 2020, she revealed that she wrote four albums worth of material in an attempt to adapt to changing trends in the music industry; she wanted to "make pop records that feel relevant in an era when hip-hop reigns".

Others included Ojivolta, King Henry, Daniel Gleyzer, Zach Skelton, Tyler Johnson, Wells, Whethan, Jon Castelli, and Some Randoms.

[10][11] Trainor connected with Nicki Minaj through a shared manager and met Nicole Scherzinger while filming their television shows at the same lot; both artists feature on the album.

[17] According to AllMusic's Matt Collar, Trainor embraced "club-ready dance rhythms and contemporary R&B hooks" with it, incorporating "screwdriver bass lines, shimmery synths, and bright vocal overdubs" and moving towards the "slick, hip-hop-infused funk" musical styling of Bruno Mars.

[21] The album opens with "Wave", a house ballad[9][22] about the emotional effects of a fledgling relationship, which features Sabath as the remorseful lover requesting a final chance from his partner.

[23][24] "Nice to Meet Ya" is an R&B song with hip-hop beats, which features a rap verse from Minaj and a chorus whispered by Trainor.

[20][25] The fifth track, "Workin' on It", featuring Lennon Stella and Sasha Sloan, is a minimalistic and downtempo song about Trainor's issues with self-acceptance and how she is still working on ameliorating herself.

On "Here to Stay", an old-school R&B song, Trainor describes a committed romantic relationship: "I fall apart in front of your face / But you think it's cute, you make fun of me.

[9][18] It incorporates diphthongs during several words ending with the syllable "od" in its chorus;[27] critics likened its electronic soundbed to the work of Daft Punk.

[8][15] The deluxe edition contains the dance-pop song "Make You Dance", "Underwater" featuring Dillon Francis, "You Don't Know Me", and acoustic versions of "Ashes" and "Workin' on It".

[39] In August, she postponed its release and stated: "I'm in such an amazing place and I can't stop writing songs… I've decided to move my new album Treat Myself until I get everything out of my head and recorded in the studio.

[60] Idolator's Mike Wass named Treat Myself the 66th best pop album released in 2020 and believed it was "one of those projects that is destined to attain cult status in years to come".

Alvarez believed Treat Myself offered a contemporary interpretation of Trainor's earlier music, which she considered a novel and infectious method to captivate listeners: "the intricacy of instruments, sounds, beats, lyrics and production all received superior treatments".

[67] Collar thought the album "continues to evolve her sound" but fails to recreate the charisma of Title (2015) due to its "sophisticated production style".

[19] NME's Hannah Mylrea called it a vexing listen due to its "sickly sweet and filled with cliché lyrics" and "insipid songs".

[22] Blum opined that Treat Myself depends on the concept of "female duplicity" and fails to truly empower women: "Trainor is left constantly placating [...] This is self-flagellation disguised as motivation.