He made his first team debut for Western Province during the 2012 Vodacom Cup, in their game against. He made a total of three appearances in that campaign, scoring one try. He was then also included in the squad for the 2012 Currie Cup Premier Division. In August 2013, he signed a contract that will see him remain at and the until 2015. De Allende represented the Ikey Tigers in the 2012 Varsity Cup. After the 2019 Rugby World Cup, where de Allende was a member of the victorious South African team, he joined Japanese Top League side Panasonic Wild Knights. De Allende will join Irish Pro14 side Munster, whose head coach is former Springboks forwards coach Johann van Graan, on a two-year contract from the 2020–21 season.
Representative rugby
In May 2014, De Allende was one of eight uncapped players that were called up to a Springbok training camp prior to the 2014 mid-year rugby union tests. He was subsequently named in the final squad, but suffered a medial knee ligament injury and had to withdraw from the squad. However, he was once again selected in the Springboks' next squad for the 2014 Rugby Championship and was named in the starting line-up for their opening match of this competition against in Pretoria. In 2015, he was selected in the starting XV of a South African side against the World XV for a game held on 11 July 2015. He scored two tries in the game earning praise from the World XV and former Australian coach Robbie Deans who commented that "Damian has been playing remarkable rugby the whole year and he keeps doing the right things. He can add a new dimension to the Boks." Having only been on the field for 13 minutes, De Allende was controversially red-carded in the 75th minute against New Zealand on 8 October 2017 by referee Jerome Garces for a late hit on first-five Lima Sopoaga, intending to charge down Sopoaga's intended drop goal. De Allende was not suspended, as SANZAAR stated he should not have received red for the attempted charge down. The final score of the match was New Zealand 25–24 South Africa. De Allende was named in South Africa's squad for the 2019 Rugby World Cup. South Africa went on to win the tournament, defeating England in the final.
Pld = Games Played, W = Games Won, D = Games Drawn, L = Games Lost, Tri = Tries Scored, Con = Conversions, Pen = Penalties, DG = Drop Goals, Pts = Points Scored
