Raised in Waikato, O'Donnell attended Hamilton Boys' High School and played 47 games for the 1st XV along with younger brother Declan, who also went on to become a professional rugby player. O'Donnell was a NZ under 20s trialist in 2008 and was named as a non-travelling reserve for the IRB Under 20 World cup 2009 in Japan, alongside Cody Rei who later joined the full Squad. Not being recognized by Waikato Academy until after making the NZ under 20s trials, O'Donnell decided to shift to Taranaki in 2009 after school, in pursuit of an ITM cup contract. After a good local season with the Clifton Rugby club, He was signed for the 2009 Taranaki ITM Cup Squad. He made his debut for the Bulls in a match against in Pukekohe.
Senior career
O'Donnell spent the 2009 and 2010 seasons with Taranaki and during that time his appearances were largely confined to cameos from the replacements bench. He was also signed by the Taranki Bulls for the 2011 and 2012 season. O'Donnells Career was hindered in 2011, Plagued by a foot injury and coupled by a brawl with bouncers in an incident at A Hamilton Bar with his brother Declan, he made only 2 appearances off the bench in 2011. An injury in preseason training leading into a ranfurly shield game against whanganui also set O'Donnell back in 2012. Where he was then "leap-frogged" by Jamison Gibson-Park. O'Donnell eventually shifted back to waikato, for whom he started the first 4 games at half back until he was replaced by late edition to the squad Brad weber. O'Donnell played an additional 3 games off the bench as a winger replacement in 2013. Again he couldn't make the Waikato squad for the following provincial rugby season 2014. After a year away from provincial rugby, he returned to Taranaki in 2015, providing cover for the injured Jamison Gibson-Park. His real breakthrough in the 15-man game came in 2016 when he was able to win the starting number 9 jersey at Taranaki from Te Toiroa Tahuriorangi and put in a series of good performances in a season which saw the Bulls reach the Premiership semi-finals. O'Donnell broke his leg in the quarter final against Auckland and missed the semi final which Taranaki lost to the Tasman Makos. O'Donnell started his super rugby season recovering from his broken leg and made no appearances for the Hurricanes in 2017. Returning with a vengeance for the Mitre 10 Cup at the end of the season O'Donnell put together some great cameo performances for the Port Taranaki Bulls, But was unable to cement a regular starting spot from Te Toiroa Tahuriorangi. At the conclusion of Mitre 10 Cup O'Donnell was a late addition to the Chiefs pre-season as a replacement player for 2018. Yet again, O'Donnell went full circle and made the decision to move back home to Waikato. But Plagued by achilles tendonitis O'Donnell struggled to find form. He made only 4 appearances and starting only 2 games for Waikato, Who went on to win the championship division over Otago
Super Rugby
After a long and meandering provincial career, O'Donnell finally landed a Super Rugby contract with the defending champions, the in 2017.
International
O'Donnell was an All Blacks Sevens representative from 2011 until 2012, competing in 5 World Rugby Sevens Series events and scoring 3 tries.He also held the All Blacks Sevens beep test record. With an unprecedented score of 15.6 the highest Sir Gordon tietjens had ever seen in a NZ sevens camp. He said "Caleb Ralph nearly hit 15 once and Roger Randle is also right up there but 15.6 is staggering".. https://www.topendsports.com/testing/results/beep-test.htm https://www.nzherald.co.nz/rugby/news/article.cfm?c_id=80&objectid=10805415
