Lathan Moses Stanley Echols was born on January 25, 2002, in Seattle, Washington, to a white mother and a black father.^[5][6] He was raised by his mother in the north end of Seattle. He began rapping in his early teens and started his music career in the eighth grade. Echols first attended Mountlake Terrace High School, then transferred to Shorecrest High School in the tenth grade. He later dropped out of school following the success of his song "Pull Up", and went on to pursue his career, heading to Los Angeles to record.^[5][6]

"Pull Up" was Mosey's first released track and served as his debut commercial single.^[7] Its music video reached over 25 million views on YouTube in the first 16 months upon its release.^[2]On March 14, 2018, Mosey released his second commercial single "Boof Pack". Its music video was released on the WorldStarHipHop channel, and received over 13 million views on YouTube in just over a year after its release.^[8] Around four months later, he released "Noticed" as his third commercial single alongside a music video directed by Cole Bennett. The song peaked at number 80 on the US Billboard Hot 100, while its music video has gone on to become one of the most popular videos on Lyrical Lemonade, amassing almost 290 million views to date.^[9] In the video, "Mosey and his friends live the good life as they relax in a luxury apartment, which overlooks a beautiful beach".^[10]

On October 19, 2018, Mosey released his debut studio album titled Northsbest, which includes the four previously released singles and seven other tracks.^{[citation needed]}

Certified Hitmaker was released on November 8, 2019, containing the three singles and eleven other tracks.^[11]

On January 31, 2020, Mosey was featured on "Safe With Me", a song from Puerto Rican rapper Eladio Carrión's debut studio album Sauce Boyz. On February 7, 2020, Mosey released the single "Blueberry Faygo", after it garnered traction and went viral after being leaked on streaming platform Spotify throughout 2019. It later became his highest-peaking song on the Billboard Hot 100, peaking at number 8 and charting well internationally.^[12]

On June 26, Mosey released the song "Back at It", featuring fellow American rapper Lil Baby, as the first single of the deluxe edition of Certified Hitmaker.^[13] The song charted at number 9 on the US Bubbling Under the Hot 100. The deluxe's second single, "Top Gone", was released on August 5, featuring Puerto Rican rapper Lunay.^[14]The deluxe edition of Certified Hitmaker, marketed as Certified Hitmaker (AVA Leak), was released on August 14, 2020. It includes the two singles as well as three additional tracks.^[15]

On August 30, during an interview with The Hollywood Fix, Mosey teased a new project by playing a snippet of new music. The project was later announced to be a new mixtape titled Universal.^[16] The mixtape will act as a transition between Certified Hitmaker, and his upcoming third studio album: The Land of Make Believe.^[17]

To start of 2021, Mosey was featured on the remix of "Blueberry Eyes" on January 22, the 2020 hit single by American singer MAX, which also features South Korean rapper Suga from BTS and American singer Olivia O'Brien. On January 25, 2021, his nineteenth birthday, Mosey celebrated by releasing "Holy Water", as the second single for Universal.^[18] Four days later, Mosey was featured on "Boom Boom", the fourth track on the EP Lucky 7 by American rapper Rich the Kid. On February 5, Mosey released "We Outside", a song in collaboration with fellow American rapper Smokepurpp. A week later, he released the album's third single, "Enough", which coincided with a Valentine's Day release.^[19]

On April 2, 2021, Echols was charged with one count of second-degree rape in Lewis County, Washington, for engaging in sexual intercourse with an individual that was incapable of giving consent.^[20][21] He pled not guilty^[22] and passed two polygraph tests.^[23] Echols was tried in a joint trial alongside co-defendants Francisco P. Prater and Joshua D. Darrow.^[24] The trial began in February 2023 and in March 2023 he was found not guilty.^[25]

Echols released the single "Flu Game (song)" in 2023, a song that pays tribute to Michael Jordan.^[23] He followed up in 2024 with the single "Life Goes On", a song from his upcoming EP. He also signed a global distribution partnership with Cinq Music Group the same year.^[26]

In 2020, Mosey opened his own record label Certified Hitmakers. His first signee was Jae Lynx, who released his debut single "Bad Girl Vibes" under the label on November 6, 2020.^[27]On January 14, 2021, Lynx released his second single "Regrets" with YNW BSlime. As of 2024, Jae Lynx is still the only signee to the Certified Hitmakers.^[28]