Robertson said taking on the head coach role would be like a dream come true.
"This is a team I have played for, am passionate about and looking forward to leading. The Head Coach of the Crusaders is regarded as one of the best jobs in the world, so I couldn't be more excited to be taking it on.
"When I think about the remarkable men who have done the job before me, including current Head Coach Todd Blackadder, I am humbled and honoured to be stepping into their shoes. The previous and current coaching teams have built an impressive legacy and I take the responsibility of continuing and building on that legacy very seriously. The playing group is a great bunch of men who I am excited to work with; I will give everything to this role and am ready to take on the opportunity," Robertson said.
Robertson will continue in his role as Head Coach of the Canterbury team for the 2016 Mitre 10 Cup season, before starting in his new job.
A process to complete the makeup of the Crusaders 2017 coaching team will take place at the end of the current season.