Walker attended Minisink Valley High School in Slate Hill, New York, where he played football, baseball, and swam.

[2] After the season, Walker was selected by the New York Mets in the 37th round of the 2017 Major League Baseball draft.

[3] He signed and made his professional debut with the Rookie-level Gulf Coast League Mets where he posted a 9.42 ERA over 14+1⁄3 innings.

Walker pitched only six innings in 2019 after being in a car accident that injured his left arm, and he did not play a game in 2020 after the minor league season was cancelled due to the COVID-19 pandemic.

[6][7] Over 21 games (twenty starts) between the three clubs, Walker pitched to a 9-4 record, a 3.73 ERA, and 98 strikeouts over 115+2⁄3 innings.

[10] Walker began the 2023 season with Syracuse, where he made nine appearances and logged a 0.68 ERA with 18 strikeouts in 13+1⁄3 innings pitched.