Born in Oak Hills, California, Long played four seasons of college soccer for the UC Riverside Highlanders before being drafted in the second round of the 2014 MLS SuperDraft by the Portland Timbers with the 36th overall pick.

After loan spells with USL Pro clubs Sacramento Republic and Orange County Blues, Long was released by the Timbers and subsequently signed by rivals Seattle Sounders FC.

[6] After signing with Portland, Long was loaned to their USL Pro affiliate Sacramento Republic, where he made his debut on March 29, 2014, in a 1–1 draw against LA Galaxy II.

[10] He was a regular starter for Sounders 2 playing as a midfielder before being converted to centerback, appearing in 28 matches and recording one goal and two assists.

[15] On October 2, 2016, Long scored two goals to help New York Red Bulls II advance to the Eastern Conference Semifinals of the 2016 USL Playoffs in a 4–0 victory over Orlando City B.

[18] Long was named as the 2016 USL Defender of the Year after leading a defense that conceded the fewest goals in the league during the regular season.

On March 31, 2018, Long scored his first goal of the 2018 season for the New York Red Bulls in a 4–3 loss to Orlando City SC.

[30] He was a free agent and attracted offers from Seattle Sounders FC, Inter Miami CF,[31] Monterrey, Cruz Azul, and two unnamed English clubs.

[33] In June 2019, he was called up to his first international tournament when Gregg Berhalter named him to the final roster for the 2019 CONCACAF Gold Cup.