He played in Major League Baseball (MLB) for the Chicago Cubs, Florida Marlins, Milwaukee Brewers, and New York Yankees.

He grew up in Tijuana, Mexico, where he trained in the arts of kenpo, boxing, and wrestling due to frequent street fights.

[3] Mitre was the Chicago Cubs' 7th-round selection in the 2001 Major League Baseball Draft out of San Diego City College.

[4] His first stop through the minors was the Boise Hawks in the Short Season Northwest League, where he pitched alongside Dontrelle Willis.

Mitre returned to the majors on May 24 to make a spot start when Kerry Wood was placed on the disabled list.

On June 8, Mitre out-pitched Roy Halladay in a 2–0 win over the Toronto Blue Jays, allowing two hits and a walk, while striking out six in seven innings.

[16] On June 14, 2005, he threw a five-hit complete game shutout in a 14–0 victory over the Florida Marlins and Josh Beckett.

[19] On December 7, 2005, Mitre and minor league pitchers Ricky Nolasco and Renyel Pinto were traded to the Florida Marlins for Juan Pierre.

[30] He initially attempted to rehab the injury,[31] but ultimately underwent Tommy John ligament replacement surgery on July 15 and was expected to miss 12–18 months.

[39] He hit the disabled list with an oblique strain on June 5[40] and didn't return until July 24 when he started in place of the injured Andy Pettitte.

[44] His only playing time came during the American League Championship Series against the Texas Rangers, when he made three appearances in mop-up duty.

Mitre dealt with multiple injuries, including nerve damage in his back, that brought his MLB career to an end.

On April 29, 2017, Mitre came out of retirement and signed with the Bravos de León of the Mexican Baseball League.

On July 9, 2017, Mitre was traded to the Toros de Tijuana in 5 games (4 starts) 29.1 innings he went 3-2 with a 3.38 ERA and 11 strikeouts.

[26][57][53] Mitre started Playmakers, a free youth baseball clinic for children in Chula Vista and National City.

[57][53] On September 1, 2019, while playing for the Saraperos de Saltillo of the Mexican League, Mitre was arrested on suspicion of assaulting a woman, after employees at a Quality Inn in Saltillo alerted authorities of a domestic violence situation taking place inside a suite.

[61] On July 14, Mitre was charged with femicide and aggravated statutory rape over the death and possible sexual assault of his girlfriend's daughter; he was booked into the Saltillo Prison.

[64] On January 20, 2022, Mitre was sentenced to 50 years in prison after being convicted in Mexico for femicide in the murder of his then-girlfriend's 22-month-old daughter.