Yusmeiro Alberto Petit (Spanish pronunciation: [ʝusˈmejɾo peˈtit]; born 22 November 1984) is a Venezuelan former professional baseball pitcher.

He made his professional debut in 2002 with the Venezuelan Summer League where he went 3–5 with 2.43 earned run average (ERA) in 12 games, 11 starts.

He began the season at Capital City of the South Atlantic League where he was selected to the Mid-Season All-Star team.

He pitched 2⁄3 scoreless innings for the World Team at the 2004 All-Star Futures Game on 11 July in Houston, Texas.

In November 2005, the Mets traded Petit along with Mike Jacobs and Grant Psomas for Carlos Delgado.

He made his major league debut on 14 May against the Pittsburgh Pirates, allowing one hit with two strikeouts in one inning.

He held the Atlanta Braves scoreless in three innings during second appearance on 17 May at Turner Field, recording a career-high three strikeouts.

Petit suffered first major league loss on 19 May against the Tampa Bay Devil Rays, allowing a 10th-inning walk-off home run to Aubrey Huff.

[3] He picked up his first win for the Triple-A Tucson Sidewinders on 15 April against the Colorado Springs Sky Sox, tossing six innings, allowing two earned runs off six hits with five strikeouts.

He was recalled on 22 April and made his Diamondbacks debut that night against the San Francisco Giants, allowing two runs over seven innings in the loss.

[4][5] He started the season in the major leagues for the first time in his career and posted a 0–1 mark with a 4.70 ERA in six relief appearances before being optioned to Tucson on 27 April.

He made his first start of the season for the D-backs on 2 July and earned a no-decision in a 4–3 loss against the Milwaukee Brewers after allowing only one run on two hits with four strikeouts in six innings.

The Giants won the 2012 World Series over the Detroit Tigers and although Petit was not on the playoff roster, he did receive a ring.

On 6 September 2013, making just his third major league start of the year since joining the rotation as an injury replacement, Petit came within one strike of pitching a perfect game against his former team, the Arizona Diamondbacks.

It was broken up on a single by pinch hitter Eric Chavez on a 3-2 count with two outs in the ninth inning.

[12] Making a spot start in place of the injured Matt Cain on 22 July and giving up five runs (increasing his season ERA to 4.11[12]), Petit recorded the last out of the fifth inning and subsequently proceeded to post six consecutive perfect relief appearances, of lengths varying from 1 to 4+1⁄3 innings, totalling 38 consecutive retired batters.

[13] On 28 August, Petit returned to the Giants starting rotation in place of Tim Lincecum and set down the first eight Colorado Rockies to set a new MLB record for consecutive batters retired at 46 (over a period of eight games), breaking the record of 45 formerly held by Mark Buehrle.

After giving up a third-inning double to opposing pitcher Jordan Lyles to snap the streak, Petit proceeded to complete six innings, allowing four hits and a run, to record the win and reduce his season ERA to 3.44.

[15] In Game 4 of the 2014 National League Championship Series, Petit pitched three scoreless innings in relief of Ryan Vogelsong that gave the Giants time to erase a 4–1 deficit.

[17] The Washington Nationals announced on 14 December 2015, that he accepted a one-year deal with an option for a second year, which was declined.

[22] On 7 December 2017, Petit signed a two-year contract with the Oakland Athletics which includes a club option for 2020.