Influenced by various genres including dance, hip hop, funk, and Caribbean music, Trainor conceived the album to showcase her versatility.

Reviewers were divided about Thank You; a few thought its production was an improvement from Trainor's debut major-label studio album, Title (2015), while others believed it lacked artistic identity and criticized the lyrical themes.

Meghan Trainor signed a contract with Epic Records in 2014 and released her debut single, "All About That Bass", in June that year.

[3][4][5] Trainor's artists and repertoire contact asked her to work on similar material with its co-writer, Kevin Kadish, for her debut major-label studio album, Title (2015).

[12][13] Trainor was embroiled in controversies surrounding the lyrics of "All About That Bass"[14][15][16] and the portrayal of gender roles in the music video for her song "Dear Future Husband" (2015).

[22] A fan of the music project Wallpaper, Trainor co-wrote songs with its frontman, producer Ricky Reed, and his frequent collaborator Jacob Kasher Hindlin.

[9] Upon hearing the material, L.A. Reid, the chairman of Epic Records, encouraged her to go back to the drawing board because she lacked a proper lead single for the project, a behavior that Trainor described as typical of him.

[33] Trainor cited Bruno Mars as an inspiration due to his ability to "pull off" a diverse amount of musical styles,[29] along with artists she listened to during her childhood like Aretha Franklin and Elvis Presley and ones she missed hearing on the radio—NSYNC and Destiny's Child.

[38][39][40] Rolling Stone's Christopher R. Weingarten thought it is "a brash pop statement" that expands Trainor's sound into "dance-, rap- and Caribbean-influenced tunes".

[9] Allan Raible of ABC News described Thank You's style as "funk, faux hip-hop, and some ballads", and Stephen Thomas Erlewine of AllMusic believed its "shiny, happy pop" was equally influenced by "modern R&B and Y2K throwback".

[42][43] In its lyrics, Trainor denounces her detractors and flaunts her looks and riches;[44] The Boston Globe's Marc Hirsh described it as "James-Brown-by-way-of-Bruno-Mars rubbery electro-hip-hop funk groove".

[48][49] "Better", featuring Yo Gotti, is a soca and reggae song,[9][39][45] whose instrumentation of percussion, guitar, and a "loping beat" give it a "Caribbean feel" according to PopMatters' Chris Conaton.

"I Love Me", featuring LunchMoney Lewis, is a song about confidence with a groovy baseline,[53] which The Guardian's Dave Simpson described as a "self-help-manual-with-beats" and the Knoxville News Sentinel's Chuck Campbell called a "clappy/plucky sing-along" that seems like a mashup of "Happy" (2013) and "Uptown Funk" (2014).

[40][39] The seventh track, "Kindly Calm Me Down", is a piano ballad reminiscent of the work of Adele and places emphasis on Trainor's voice as she pleads her lover to mollify her.

[50] "Mom" contains a recorded phone conversation between Trainor and her mother, along with girl group background vocals and a Motown-influenced horn segment.

[77] A performance of "Me Too" on The Tonight Show drew attention when Trainor fell to the floor while trying to grab a hold of a microphone stand.

[86] Spin's Dan Weiss called it a huge advancement from Title, for which he credited Reed's funk-influenced production that did not incorporate synthesizers.

[90] Erlewine believed Thank You is more modern and consistent as it is rooted in refined and fashionable sensibilities, but he added that it is too self-congratulatory and exposes the "seams in [the] construction" of Trainor's music.

[88] Campbell thought Thank You proved Trainor had not yet established her identity and portrayed a witty and determined pop star with lacking certitude.

[39] Patrick Ryan of USA Today wrote that the album attempts to be many things and falls short but portends a bright future for her.

[52] Writing for Entertainment Weekly, Isabella Biedenharn believed Trainor had a "bit of an identity crisis"; she praised her jocular songwriting on the upbeat tracks but added that its attempts at being intimate fall short.

Slant Magazine's Alexa Camp stated that with Thank You, Trainor continued promoting a narrow and materialistic type of feminism.

[40] Hazel Cills of MTV News wrote that other pop and R&B female empowerment songs would outshine the precise "'you want to be me' positioning" of Thank You, and she described the album as an assortment of "trend-grabbing dresses" that would fall apart by the following year.