Nessman was born in Courtenay, British Columbia. The youngest of four children. In late 2006 Nessman was first discovered as a model after a friend of his sister sent in pictures of him to a local agency in Canada. At the time 18-year-old Nessman was still attending high school at Georges P Vanier Secondary and didn’t pursue his modelling career until graduating.
Nessman is best known as the current face of Giorgio Armani. In addition, he has featured in ad campaigns for Versace, D&G, Givenchy, Calvin Klein, Ralph Lauren, Lanvin, Yves Saint Laurent,Barneys, Gap and John Galliano. He was featured in the 2012 music video of Madonna‘s new song, Girl Gone Wild, as directed by fashion photographers Mert Alas and Marcus Piggott.
He has walked in shows for Salvatore Ferragamo, Roberto Cavalli, Tommy Hilfiger, Emporio Armani, Viktor & Rolf, Lacoste, DSquared, Narciso Rodriguez and Michael Kors and appeared in Vogue,Details, Numéro, V Man and L’Officiel Hommes.
In 2012 Nessman became the face of the Giorgio Armani fragrance Acqua di Gio Essenza. The campaign was shot and directed by Bruce Weber (photographer) as of 2014 Nessman stars in both print and video campaigns for the fragrance.
From late 2010 to 2014 Nessman starred in multiple print and film campaign advertisements for American fashion designer Michael Kors alongside Karmen Pedaru. In 2015 Nessman starred alongside British supermodel and actress Cara Delevingne as the face of John Hardy (jewelry) for the Spring/Summer 2015 campaign. The campaign was shot by Sebastian Faena entirely in Bali.
In 2011, Nessman was the second most successful male model in the world behind Sean O’Pry on models.com list of the Top 50 international male models. In 2013, Forbes named Nessman Number 3 on there The World’s Highest-Paid Male Models list coming in behind David Gandy Number 2, and Sean O’Pry Number 1. In 2014, Nessman was nominated for a Model Of The Year award. As of 2015, Nessman was featured on Models.com’s list of Sexiest Men, Top Icons Men, and The Money Guys.