Murphy began baseball-related activities at the age of four, when his father Mike signed him up for a class offered by the
Riverside Recreation Department.[1] Mike Murphy became his son's coach in
Little League and travel league baseball when Owen was seven.[1] When he was 13, Murphy began the Rake City baseball training program.[1] Murphy attended
Riverside Brookfield High School. He played high school
baseball as a pitcher and shortstop,[2] and was also a
quarterback and
wide receiver for the
football team.[1][3] During his junior season in 2021, he pitched to a 6–1 record and a 0.33 ERA alongside hitting nine home runs.[4] As a senior in 2022, he went 9–0 with a 0.12 ERA, surrendering ten hits while striking out 137 batters over 58+1⁄3 innings and was named the Illinois Gatorade Player of the Year.[5][6] He committed to play
college baseball at the
University of Notre Dame.[7][8]
Murphy made his professional debut with the
Florida Complex League Braves and he also played with the
Augusta GreenJackets. Over 12 innings, he gave up six earned runs. To open the 2023 season, he returned to Augusta and was promoted to the
Rome Braves in August.[12] Over 21 starts between the two teams, Murphy went 6-4 with a 4.72 ERA and 113 strikeouts over 89+2⁄3 innings.[13]