He played in Major League Baseball (MLB) for the San Francisco Giants, Boston Red Sox and Seattle Mariners.

On December 13, 2004, Machi was selected by the Tampa Bay Rays organization in the minor league phase of the Rule 5 draft.

On October 31, 2006, Machi signed a minor league contract with the Toronto Blue Jays organization.

[1] He split the year between the Triple-A Indianapolis Indians and the Double-A Altoona Curve, accumulating a 3-4 record and 2.09 ERA in 41 appearances.

He played in 3 games for the Triple-A Fresno Grizzlies before he was loaned to the Diablos Rojos del México of the Mexican League for the rest of the season.

[4] On September 3, Machi made his major league debut, against the Arizona Diamondbacks, pitching a perfect inning.

At the start of the 2014 season, Machi picked up three relief wins in his team's first 15 games, becoming the first Giants pitcher to do so since Bob Shaw in 1964.

[7] On July 28, 2015, Machi was claimed off waivers by the Boston Red Sox and starter Clay Buchholz was transferred from the 15- to the 60-day disabled list to make space for him on the 40-man roster.

[10] On December 14, 2015, Machi signed a minor league contract with an invitation to spring training with the Chicago Cubs organization.

[12] On June 16, 2016, Machi signed a minor league contract with the San Francisco Giants organization.

On July 21, 2017, Machi was traded to the Chicago White Sox, along with fellow veteran pitcher Mark Lowe, in exchange for cash considerations.

On February 7, 2018, Machi signed with the Diablos Rojos del México of the Mexican Baseball League.