Rubio began his football career with Universidad Católica. However, when he was 14, he took the decision to move to his favorite team Colo-Colo. After one year in the bench with Colo-Colo, in the next season Diego was consecrated in the youth team. After many seasons in the youth ranks, he was promoted to the first professional team in January 2011.
Colo-Colo
Rubio made his professional debut for Colo-Colo in a pre-season friendly against Deportes La Serena as a starter. In other pre-season game, Diego scored his first unofficial goals for the club, in a 3–1 won against Unión Española, in where he scored two goals for his team, being named the man of the match. His Chilean Primera División came on 14 February 2011 against Unión San Felipe, as an 84th-minute substitution in a 2–0 away defeat. In a Copa Libertadores game played against Santos in Brazil, he scored his first professional goal, but the match finished in a 3–2 loss. On 19 April, Rubio scored his first two goals in the Primera División against La Serena, at 30th and 62nd minute, being named the man of match, in a 4–1 home win. He finally was consecrated in the club in an international game for the Libertadores against Táchira, Rubio gave the 2–1 victory to the club, scoring the two goals of Colo-Colo, after an early goal of Edgar Pérez Greco at 4th minute. After his club's performances, was rumored that Udinese are interested in Rubio. He played his first derby game against his former youth club Universidad Católica, participating in the equalizer goal of Colo-Colo giving an assistance to Ezequiel Miralles at 81st minute, putting the 1–1 draw. The coach Américo Gallego nominated to Rubio for play the major derby of the Chilean football against Universidad de Chile, however, he only playing 30 minutes in a 2–1 loss.
Sporting CP
On 5 July 2011, Rubio joined Portuguese club Sporting Clube de Portugal for €1.5 million, signing a five-year contract with a €30 million minimum fee release clause.
Loan to Pandurii
On 2 September 2013, Romanian Liga I club Pandurii Târgu Jiu confirmed Rubio was signed on a loan from Sporting, with an option to buy. He debuted in Liga I in the match against Dinamo Bucharest, won by Pandurii 2–1.
On 8 March 2016, Rubio signed a season-long loan with Major League Soccer side Sporting Kansas City as a Designated Player. He signed with the club on a permanent deal on 1 September 2016.
Colorado Rapids
Ahead of the 2019 season, Rubio was traded to Colorado Rapids in exchange for Kelyn Rowe, $200,000 of General Allocation Money and $100,000 of Target Allocation Money.
Diego is the son of Hugo Rubio. Currently working at the Passball company as a football agent, Hugo was a successful football player, having spent most of his extensive career in his country with a short spell in European football, specifically in Italy and Switzerland. Hugo also was a member of the Chile squad at the Copa América of 1987 and 1991. Diego has two footballer brothers, Eduardo, and Matías, who plays for Unión La Calera. Diego Rubio is also godchild of the Chilean football legend Iván Zamorano. On 15 May 2011, was reported that Rubio was on a list of most popular Chilean players on Twitter with 1,247 fans, in the 12th place of 14 players. The list was led by Jorge Valdivia, in the 1st place with more of 50,000 fans. On 24 May 2013, Diego got married with Rocío Navarro in Seville and on 6 June 2014 his first son Thiago was born. Rubio earned his U.S. green card in September 2017. This status also qualifies him as a domestic player for MLS roster purposes.
