On May 10, 2014, Underwood was signed as an undrafted free agent by the San Diego Chargers. On August 30, 2014, he was waived. On September 3, 2014, Underwood was signed to the Philadelphia Eagles' practice squad. On September 9, 2014, he was released from practice squad. On September 23, 2014, Underwood returned to the Chargers and was signed to their practice squad. On December 29, 2014, he signed a future contract. On September 5, 2015, he was waived. On September 6, 2015, he was placed on injured reserve. On September 10, 2015, he was waived from injured reserve. On December 1, 2015, Underwood was signed to the Raiders' practice squad. On August 29, 2016, he was released by the Raiders.
Reality television
Underwood was a contestant on the 14th season of The Bachelorette, starring Becca Kufrin. After getting eliminated in week 8 after hometown dates, Underwood was cast in season five of Bachelor in Paradise. After being linked to fellow contestant Tia Booth, Underwood broke it off, and both left Paradise separately in the 4th week. On September 4, 2018, ABC announced Underwood would star in the 23rd season of The Bachelor. The announcement received mixed reactions on social media. On September 21, 2018, ABC announced that Colton had started filming The Bachelor and had already met three of his contestants on The Ellen DeGeneres Show.
Philanthropy
In January 2016, Underwood founded the Colton Underwood Legacy Foundation to raise money for cystic fibrosis research and medical equipment. Although not named after her, Underwood started the foundation in honor of his cousin Harper, who was diagnosed with the disease at 4 years old. In January 2018, the foundation began the Legacy Project, with the goal of delivering Afflovests to children in 50 US States.
Personal life
Underwood has spoken publicly about his choice to remain a virgin, and how appearing on The Bachelorette helped him discuss the topic. Underwood began dating speech pathology student Cassie Randolph after meeting on season 23 of The Bachelor. When Randolph initially ended their relationship during the final three, Underwood broke things off with the other two women and asked Randolph for a second chance without the pressure of an engagement. Underwood and Randolph were in a relationship from November 2018 until May 2020. On March 20, 2020, Underwood said he had tested positive for COVID-19.