On 1 November 2018, Brillant scored his first goal for D.C. United against the Columbus Crew with a header in the first round of the MLS 2018 Playoffs.

[12] In 2021, Brillant's playing time began to decline after the acquisition of Brendan Hines-Ike and the rise of Donovan Pines in the starting lineup.

[13] On 11 January 2022, Brillant announced his retirement from playing and professional football, and would be taking up a role as assistant coach to Loudoun United.

[15] On 13 March 2024 Brillant was announced as an assistant coach for the Utah Royals of the NWSL, an expansion side in its inaugural season.

[16] On 20 May 2024, Brillant was announced as the head coach for DC Power FC of the newly-formed USL Super League[17][18] Power FC and Brillant parted ways on 27 November 2024, after posting a record of 3 wins, 6 losses, and 4 draws.