Christiansen will replace Bali Padda, 61, who has served as the Company's first non-Danish chief executive since January, 2017.
LEGO's chairman, Jorgen Vig Knudstrop revealed that Padda's short tenure was not down to his performance but 'a realisation that, because of his age, he could do the job for a few years at most'. Padda has been moved to a "special advisory role" at the LEGO Brand Group.
The search "went faster than expected", it said. "He played an integral role in the turnaround of the LEGO Group and during his time as CEO created a solid foundation from which to continue to transform the company", Knudstorp said in a statement.
Mr Christiansen joins Lego after nine years as chief executive of Danfoss, where he increased sales and turned the technology company into a global leader in energy efficiency by focusing on digitalisation.
Before Danfoss, Mr Padda's replacement Mr Christiansen was head of hearing aid firm GN Store Nord. "I suddenly saw a chance to shorten the process", Mr Knudstorp said.
"Bali has been part of the Lego Group family for the past 15 years. I have loved building with LEGO bricks since I was a child". "I was just very fortunate that, relatively early, we found the right person", Mr Knudstorp said. "At Lego, we make significantly more money than our closest competitors combined".