After graduating from George Walton Comprehensive High School,[2] Kieboom played college baseball at Clemson University.

[5] He suffered an injury that required him to undergo ulnar collateral ligament reconstruction, popularly known as "Tommy John surgery"[6] – a rarity for a catcher – in 2013, forcing him to scrap plans to play for the Netherlands in the 2013 World Baseball Classic[7] and to miss virtually the entire 2013 season, although he did play in four games with the Gulf Coast League Nationals[6] in the rookie-level Gulf Coast League late in the year, going 2-for-6 at the plate with one RBI.

[5] He thus played a small part in a year in which the Gulf Coast League Nationals finished their regular season with a record of 49-9, giving them an .845 winning percentage that was the highest winning percentage for a full regular season ever achieved by a Minor League Baseball team based in the United States.

[10] He spent 2015 with the Potomac Nationals in the Class A-Advanced Carolina League, where he played in 71 games and hit .248 with two home runs and 21 RBIs.

[11] Kieboom was promoted to the Harrisburg Senators of the Class AA Eastern League for the 2016 season, hitting .230 in 94 games with five home runs and 31 RBIs.

[13] Kieboom was on the Nationals′ roster for six days, and he had one plate appearance, drawing a walk and scoring a run in the team's regular season finale on October 2, thus ending his first stint in the major leagues with 1.000 on-base percentage.