The New Zealand full back, who scored 46 tries in 58 Tests for the All Blacks at an average of around a try every 100 minutes, is one of the world game's most exciting and entertaining players and is sure to light up an already star-studded Heineken Cup.
Cullen is the only player to score 50 Super 12 tries and is third in the world all-time international list behind Australia's David Campese (64) and England's Rory Underwood (50).
"We are absolutely thrilled that Christian - probably the best player in the world in his position - will be joining Munster," said team manager Jerry Holland.
"He will link up with our squad only when he has fullfilled his commitments in New Zealand and, if the All Blacks want him to be involved in the World Cup in Australia, we would be delighted for Christian."
The arrival of Cullen at Munster before the Heineken Cup resumes on the first weekend in December brings further international spice to the 24-team tournament that has the cream of the northern hemipshere players from England, France, Ireland, Italy, Scotland and Wales.