In April 2015, Alabama Shakes released their second album, Sound & Color. It debuted at number one on the Billboard 200, and received favorable reviews from the music press. The band went on to perform on multiple late night shows, including Saturday Night Live, The Tonight Show Starring Jimmy Fallon, and The Late Show with Stephen Colbert. Howard was featured in the musical medley alongside Mavis Staples, Stephen Colbert, Ben Folds, and more in the series premiere of The Late Show with Stephen Colbert. At Lollapalooza in 2015, Howard was invited on stage to perform a duet of "Get Back" with Paul McCartney. Howard also performed at the ceremony for Eddie Murphy's Mark Twain Prize. In 2015, Howard was named the recipient of Billboard's Women in Music "Powerhouse" Award.

Howard is also the lead singer of the rock band Thunderbitch, formed in Nashville in 2012 with members of Clear Plastic Masks and ATO Records labelmates Fly Golden Eagle. The band surprise-released a self-titled album in September 2015. Although the band rarely makes live appearances, they did play a rare set at ATO Records' CMJ Music Marathon showcase in October 2015.

Brittany Howard is also a singer in the band Bermuda Triangle with Jesse Lafser and Becca Mancari, which was formed in Nashville in 2017. Their debut live performance was on July 12, 2017 at the Basement East in Nashville. The trio released their first single on September 6, 2017, titled "Rosey", which was first released on Jesse Lafser's 2015 album "Raised On The Plains". Although originally believed to be a one time performance, the trio performed a five show tour through the Southern states of America in October 2017. This small tour included shows in Carrboro and Asheville, North Carolina; Birmingham, Alabama; Atlanta, Georgia; and Knoxville, Tennessee.

In June 2019, Brittany Howard announced a debut solo album, Jaime which was released on September 20, 2019, as well as a tour across North America and Europe. Jaime was received with universal acclaim, with Pitchfork noting "The exceptional solo debut from the Alabama Shakes singer-songwriter is a thrilling opus that pushes the boundaries of voice, sound, and soul to new extremes." On July 16, 2019, Howard released the music video to the single Stay High, featuring actor Terry Crews lip-syncing to the track. On April 15, 2020, Howard released a cover of a Funkadelic's 1971 song "You and Your Folks, Me and My Folks" and a new rendition of her song "Stay High". Stay High was recommended as an appropriate musical remedy to get people through bad lockdown and quarantine feelings.