[1] Blackadder was born in Rangiora, New Zealand, where he grew up on his grandfather's dairy farm, and took after his father and uncles by playing for the local rugby club.

While there, he played club rugby and impressed age-group selectors for Nelson Bays, which led to him eventually being selected for the New Zealand Under 19 tour of Australia.

[1] In 1997 Blackadder led Canterbury to its first NPC title in 14 years when they defeated Counties Manukau 44–13 in the final.

Blackadder was part of the inaugural Crusaders team in 1996 and would go on to lead the side to its first Super Rugby title in 1998.

[6] Blackadder was first selected for the All Blacks in 1995 and made his test debut against England at Dunedin on 20 June 1998.

Following Hart's departure, Wayne Smith was appointed head coach, and Blackadder was recalled to the team and named captain, succeeding Taine Randell.

[8] Blackadder departed New Zealand for Scotland at the end of 2001, joining Scottish side Edinburgh Gunners.

In his second year in charge, the Crusaders were the only New Zealand team to advance to the playoffs, but again fell to the Bulls in the semi-finals.

Despite the disruption, the Crusaders managed to make the final that year, before falling to the Queensland Reds, who won their first title.

In the 2014 season, the Crusaders returned to the final but again fell short, this time against the New South Wales Waratahs after a controversial last minute penalty goal.

[16] When Matson was forced to return home to New Zealand due to a family illness, Blackadder took over the coaching position.

On his release from his final year of his contract with Bath, Blackadder revealed that he would be taking on the role of head coach with the Toshiba Brave Lupus in the Japanese Top League.

[18] Todd's son Ethan Blackadder currently plays for Tasman in the National Provincial Championship, and in 2018 made his debut for the Crusaders in Super Rugby.