[6][7] In April 2011, Greenwood signed a National Letter of Intent to play college basketball for the University of New Mexico.

He had a season-best game in win against Boise State on 16 January 2013, recording 15 points and a team-high seven rebounds, all while battling the flu.

He also hit a layup to send the game into overtime, where he scored five points in the extra period to clinch the win.

Greenwood graduated top ten in Lobo history in career minutes played (3,843), assists (372) and made three-point field goals (187).

[9] After receiving a pre-draft workout invite from the Utah Jazz,[10] Greenwood signed a three-year contract with the Perth Wildcats of the Australian National Basketball League on 1 June 2015.

[13] However, on 20 August 2015, Greenwood parted ways with the Wildcats to pursue a career in the Australian Football League (AFL).

[14] After winning Basketball Australia's Junior Male Player of the Year in 2008, Greenwood joined the Australian Boomers for their 2009 program.

By mid-August 2015, however, Greenwood had lost the motivation to play basketball and subsequently retired from the game to pursue AFL.

[19][20][21] In 2016, Greenwood made a smooth transition into the Crows' State League side after an eight-year hiatus from competitive football.

He showed strong physicality and developed his ball skills throughout the year, averaging 16 disposals and kicking 25 goals from 21 games, and helped the club reach the SANFL finals for the first time.

[22] On 10 May 2017, the Crows promoted Greenwood to their senior list as possible cover for the concussed Tom Lynch, naming him as an emergency for their Round 8 clash.

[25][26] In his debut, he kicked three first-half goals and finished with 15 disposals, two marks and nine tackles in helping Adelaide defeat Brisbane 140–60.

[27] Greenwood quickly became an important part of Adelaide's midfield and impressed in his first season at AFL level, having a mature body and kicking with high efficiency.

[31] However, in a shock move, Greenwood instead opted to leave the Suns and sign a two-year deal with North Melbourne.

[10] He subsequently started a charity to raise funds for the UNM Cancer Center in honour of his mother, which received over $50,000 in donations throughout the course of the senior season.