Demus Jr. attended Friendship Collegiate Academy Public Charter School in Washington, D.C.[1] As a senior, he had 66 receptions for 1,167 yards and 12 touchdowns.

[4][5] Demus Jr. returned to Maryland as a starter in 2021,[6] leading the Big Ten Conference in receiving yards before suffering a season-ending knee injury in a game against Iowa.

[13][14] On December 6, 2023, Demus signed with the Philadelphia Stars of the United States Football League (USFL).

[15] The Stars folded when the XFL and USFL merged to create the United Football League (UFL).

[17] Demus played in three games for the Massachusetts Pirates of the Indoor Football League in 2024, catching one pass for 11 yards.