The Orioles promoted him to the MLB on June 20. He made his major league debut on June 24, pitching one scoreless inning, striking out one batter, and was optioned back to Bowie the next day. He was named to the Eastern League All-Star Game. On July 31, he was recalled after the Orioles traded Tommy Hunter and designated Bud Norris for assignment. He pitched 1 innings while striking out two batters and earning his first career Major League win against the Detroit Tigers. Givens went 2-0 in 2015 with a 1.80 ERA in 22 games, with 30.0 innings pitched. Givens struck out 38 batters while only walking six and had a WHIP of 0.867.
2016
Givens made the Orioles Opening Day roster and made his first relief appearance on Opening Day. He threw 1 innings, giving up two runs while striking out two batters. The Orioles would eventually win the game 3-2 on a walk-off single. After allowing three runs in his first two relief appearances of the season, Givens saw his ERA sitting at 13.50. Givens would go on to throw ten consecutive scoreless innings, before giving up another run. He ended the month of April, having appeared in 12 games, throwing 12 innings, striking out 21, walking seven, and pitching to a 3.00 ERA. Givens also went 2-0 in the month. In May, Givens went 1-0, while pitching to a 1.93 ERA in 11 innings in eight appearances. Givens earned the win for the Orioles on June 2 and 3rd, making him 5-0 on the year and 7-0 for his career. According to STATS, LLC, Givens was the first Orioles pitcher to begin his Major League career with seven consecutive wins as a reliever. Givens would win three more games out of the bullpen in 2016. Givens finished his 2016 campaign with 96 strikeouts and a 3.13 ERA in 74 innings in 66 appearances. He pitched to a 1.27 WHIP and an 8-2 record while striking out 11.6 batters per nine innings pitched. Givens made his postseason debut in the Wild Card Game against the Toronto Blue Jays. He entered the game with a 2-2 tie and runners on the corners. He forced a first-pitch double play. He ended up striking out three batters in 2 innings pitched, in what ended up being a 5-2 Orioles loss in 11 innings.
2017
Out of relief, Givens earned his first victory of the season on April 8, against the New York Yankees after throwing a perfect inning while striking out two batters. Givens pitched to a 2.25 ERA before the break, striking out 44 batters in 44 innings pitched, picking up six wins and three saves along the way. Overall, he finished with a 2.75 ERA in 69 games, striking out 88 in innings.
2018
He began the 2018 season as the Orioles' setup man. With a 0-7 record in 69 appearances, he also had 9 saves in 13 attempts, eight of ten as the team's closer after the late-July fire sale trades of Zach Britton, Brad Brach and Darren O'Day.
2019
Givens was tasked to be the Orioles closer to begin the 2019 season. He saved 11 of 19 opportunities, but his eighth and ninth inning ERAs went from 5.55 and 2.96 respectively the previous year to 1.93 and 6.69. He returned to the setup role for his final five outings. He appeared in 58 games with 86 strikeouts in 63 innings.
Personal
Mychal was raised by great-grandmother Liduvina Padilla and her late husband Pedro Padilla. Mychal married his long time girlfriend Tiffani in 2014.