He remained a full-time starter in his sophomore season, starting and playing in all 16 matches his sophomore year, having three goals and six assists. During his junior year, he started 10 of the 11 matches, contributing to 6 goals and two assists. He was named to the All-Pac-12 First Team both his sophomore and junior season. During his senior year at Oregon State, Djeffal started in all 19 matches, contributing to six goals and six assists. Upon conclusion of the 2021 NCAA Division I men's soccer season, Djeffal was named the Pac-12 Conference Men's Soccer Player of the Year[3] and an semifinalist for the Hermann Trophy, an annual award for the best college soccer player in the United States.
On 11 January 2022, Djeffal was drafted in the second round with the 36th overall pick for D.C. United in the 2022 MLS SuperDraft.[5] After impressing in preseason training, he signed a contract with United on 25 February 2022.[6]
On 26 February 2022, Djeffal made his professional debut for United, coming on in the final 26 minutes in a 3–0 win over Charlotte FC.
Following the 2022 season, his contract option was declined by D.C. United.[7]
Austin FC
On 17 November 2022, Djeffal was selected by Austin FC with the first pick in the MLS Re-Entry Draft Stage 1.[8] He made his debut for the club on March 25, 2023, coming on as a substitution in the second half against the Colorado Rapids.[9]
On 21 May 2023, Djeffal made his first start for Austin, replacing Jhojan Valencia in central midfield. On November 17, 2023, Austin FC announced they would not exercise the 2024 option for Djeffal.[10]