The New York Mets selected Plawecki in the first round, with the 35th overall selection, in the 2012 Major League Baseball draft. In 2013, he played for the Savannah Sand Gnats of the Class ASouth Atlantic League. He was promoted to the St. Lucie Mets of the Class A-AdvancedFlorida State League, and to the Binghamton Mets of the Class AAEastern League for the Eastern League playoffs. In 2014, the Mets invited Plawecki to spring training. He started the 2014 season with the Binghamton Mets, where he hit.326 with six home runs and 43 RBIs in 224 at-bats. Plawecki was selected to play for the U.S. Team in the 2014 All-Star Futures Game, along with Noah Syndergaard. After batting.326 for Binghamton, the Mets promoted Plawecki to the Las Vegas 51s of the Class AAAPacific Coast League on June 24. The Mets invited Plawecki to spring training in 2015, and reassigned him to minor league camp so that he could start the 2015 season with Las Vegas. After Travis d'Arnaud went on the disabled list with a broken hand on April 19, 2015, the Mets announced they would promote Plawecki to the major leagues. Plawecki made his Major League debut on April 21, 2015 against the Atlanta Braves. He got his first career hit off Trevor Cahill and finished the game 2-for-4, with two runs scored. During a game against the New York Yankees on April 25, 2015, Plawecki hit his first career home run off CC Sabathia en route to an 8-2 victory. Plawecki became the first player to hit his first career home run in a Mets-Yankees Subway Series game. Plawecki began experiencing dizziness in June, which sidelined him from playing for several games. He was demoted to the Las Vegas 51s on August 11, and recalled on September 1 due to expanded rosters in September. Plawecki finished the season with a.219 batting average with three home runs and 21 RBIs in 73 games played. Plawecki had surgery on his paranasal sinuses during the 2015-16 offseason to address his dizziness. He batted.197 in 48 games for the Mets in 2016, spending the rest of the season with Las Vegas. In an April 30, 2017 game against the Washington Nationals at Nationals Park, Plawecki was brought in to pitch for the first time since he was 14 years old. He was the first Mets position player to pitch since Anthony Recker in 2013, also against the Nationals at Nationals Park. He threw only fastballs, giving up four runs over two innings. One of those was Anthony Rendon's third home run of the game. The Mets lost 23-5. Plawecki suffered a broken hand on April 11, 2018.
Cleveland Indians
On January 6, 2019, the Mets traded Plawecki to the Cleveland Indians in exchange for Walker Lockett and Sam Haggerty. On December 2, 2019, Plawecki was non-tendered and became a free agent.
Boston Red Sox
On January 3, 2020, the Red Sox signed Plawecki to one-year, $900,000 contract.
Personal life
Plawecki grew up in Westfield, Indiana, with his parents and younger brother. His father coached his youth baseball teams. Plawecki and his wife, Tayler, were married in November 2015.