The versatile back row currently serves as skipper for New Zealand province the Manawatu Turbos and is due to join the Welsh region in February 2015.
Crosswell represented the Maori All Blacks during their European Tour in 2012 and has also been involved with New Zealand Schools, Under 19s and Under 21s.
The 28-year-old has played 81 times for the Turbos since joining the province in 2006 and went on to be named in the Hurricanes squad for the Super Rugby Season in 2010. Crosswell then transferred south to join the Highlanders in 2011 and moved to the then reigning Super Rugby champions, the chiefs, in 2013. They went on to win the title once again during Crosswells stay becoming the 4th Super Rugby franchise to record back to back wins when they defeated the Brumbies 27-22 in the final.
Director of Rugby, Lyn Jones commented: “Nick is an experienced Super Rugby player and has the right type of personality and leadership qualities that we want at Rodney Parade.
“With greater depth to our squad, we can achieve higher consistent levels of performance, from week to week: signing Nick shows the Boards vision in wanting more success on the field”.