Normani was born in Atlanta, Georgia and raised in New Orleans, and is the daughter of Derrick and Andrea Hamilton. She has two older half sisters. She attended school at Trinity Episcopal School while living in New Orleans. She and her family relocated to Houston, Texas, after Hurricane Katrina in 2005. At a young age, Normani competed in dance, gymnastics and beauty pageants. She performed gospel music as a child, and recorded her first song at age 13.

Normani auditioned on the second season of The X Factor US in 2012 with "Chain of Fools" by Aretha Franklin. She advanced to the next round after getting all four approval yeses from the judges. It was during the second round of boot camp that led to her elimination. That marked the end of Normani's X Factor participation as a solo Artist. However, she was brought back to the show and put into a group with four other girls, Ally Brooke, Lauren Jauregui, Dinah Jane, and Camila Cabello, who would later become Fifth Harmony. At the end of the show's season, the group managed to make it to the finale and finished in third place.

In 2015, Normani released two dance videos performing "Commas" and "Do Not Disturb" with Fifth Harmony's Choreographer Sean Bankhead on her YouTube channel. As of December 2017, she has released three cover-mashups (of Drake's "Fake Love"/"Sneakin'", Solange's "Cranes in the Sky"/"Don't Touch My Hair" and Tory Lanez's "Say It") with the help of the producers The Invaders.

Along with Fifth Harmony, Normani had been involved with many charities like Girl Scouts of America and the Ryan Seacrest Foundation. In September 2016, Normani was named the Diversity Ambassador for The Cybersmile Foundation, an international non-profit organization providing support for victims of cyberbullying and online hate campaigns, after being racially abused online. On January 26, 2017, Normani was named as the first official Celebrity ambassador for the annual Stars & Strikes Celebrity Bowling Event & Tournament hosted by the non-profit organization A Place Called Home. On February 24, 2017, it was announced that Normani partnered with American Cancer Society as a global ambassador to help increase awareness about the importance of breast cancer screening and HPV vaccination.

Normani was featured as a cameo in R&B singer Khalid's music video "Young Dumb & Broke", and confirmed they were working on "new song ideas". On October 21, it was announced that Normani had signed to management company S10 Entertainment as a solo Artist. She also signed her own solo publishing deal to Stellar Songs as a Songwriter. On February 14, 2018, Normani released a song with Khalid called "Love Lies" for the Soundtrack of the movie, Love, Simon. The single debuted at 43 on the US Billboard Hot 100, thus scoring the highest first-week position for a debut single by a girl group member. In April 2018, it was announced that Normani had signed to Keep Cool/RCA Records for her solo debut studio album