In December 2012, Arriola was invited to train with Tijuana, after having previously trialed with the club. Following the 2012 season and despite being offered a professional contract by the Galaxy, Arriola opted to sign for Club Tijuana of Liga MX, the highest level of soccer in Mexico. Arriola was part of a string of American-born players to join the Xolos including Edgar Castillo, Herculez Gomez, Joe Corona, and Greg Garza. The Galaxy listed Tijuana’s proximity to Arriola’s hometown of San Diego, 18 miles, as one factor contributing to his decision to opt for Tijuana over the Galaxy. About his decision, Arriola himself stated, “”I felt that Xolos was the place for me. I love the club, it’s my home team and the people down there are wonderful.” The decision allowed Arriola to live on the United States side of the border with his family but cross it for training and matches.

Arriola spent years with U.S. Soccer Development Academy club Arsenal FC based in Temecula, California, a club that has produced several successful players including Carlos Bocanegra and Hector Jiménez, before joining the academy of the Los Angeles Galaxy in 2013.

Arriola made his debut for the club in a preseason friendly against Club América at Petco Park in San Diego on July 6, 2013. In the 54th minute, Arriola scored to make the score 5–0 in an eventual 5–2 victory for Tijuana. On July 19, 2013 Arriola made his professional league debut in a 3–3 draw with Club Atlas to open the 2013–14 Liga MX season. Arriola was a second-half substitute and assisted on Darío Benedetto’s goal only four minutes after entering the match. Just a few days later, Arriola scored his second professional goal in CONCACAF Champions League against C.D. Victoria.

Arriola has been part of the United States youth national team set ups and was part of the squad for the 2011 CONCACAF U-17 Championship but did not appear in any matches because of an injury. The United States went on to win the tournament. He made three starts in four matches at the 2011 FIFA U-17 World Cup in Mexico. In 2013, Arriola joined the United States U18 squad for a trip to Europe for friendlies against France and Uruquay. Despite playing for the youth teams of the United States, Arriola applied for Mexican citizenship which would allow him to play as a domestic player in Liga MX rather than occupying one of the five foreign player spots.

Arriola made his senior team debut on May 22, 2016 against Puerto Rico, scoring his first international goal and notching an assist for a Bobby Wood goal.

On August 9, 2017, Arriola signed for Major League Soccer side D.C. United for a club record fee of $3,000,000 plus allocation money for his rights to LA Galaxy. Arriola debuted for United on August 13, 2017 in a 1–0 loss against Real Salt Lake. He scored his first goal for DC United in their season finale, and last game in RFK Stadium on October 22, 2017, against the New York Red Bulls. The game ended in a 2–1 loss. He ended his 2017 season with DC United with 11 appearances, two assists and only one goal. In the 2018 D.C. United season, Arriola’s performances greatly improved. On July 14, 2018, in a 3–1 win against Vancouver Whitecaps, Arriola scored a personal record two goals for United in their inaugural match at Audi Field. He ended the 2018 season with 28 appearances, 7 goals, and 8 assists.

During a 2020 pre-season game against Orlando City on February 15, 2020, Arriola suffered a serious knee injury. His injury was later revealed as a partially torn ACL. On February 22, 2020, D.C. United announced that Arriola will miss the entire 2020 MLS season.

On July 27, 2020, Arriola and D.C. United agreed to a multi-year contract extension through the 2023 season and an option for the 2024 season.