He has done advertising campaigns for Just Cavalli, Versace, Giorgio Armani, Guerlain, Bally, Etro, Trussardi, Diesel, Mangano, Lagerfeld, Pepe Jeans but notably H&M, Zara, Guess, and Tom Ford for his consecutive seasons with the brands.

[6] Kortajarena's other runway credentials include walking for Chanel, Versace, Balmain, Bottega Veneta, Dolce & Gabbana, Etro, Salvatore Ferragamo, Carolina Herrera, Giorgio Armani, John Galliano, Jean Paul Gautier, and Valentino in Milan and Paris.

With new campaigns on the stands, Terry Richardson photographed Kortajarena for Tom Ford alongside Noah Mills and became the label's signature male model for the next consecutive seasons.

[10][11][12] For the 2009 spring men's wear and eyewear advertising campaigns Jon was art directed and photographed, for the first time, by Tom Ford himself.

The ads were shot by Mert and Marcus showing models wearing the iconic white Lacoste polo shirts worn over eveningwear.

[19] Described as "an icon of charm and masculinity", Kortajarena was chosen as the protagonist for the special video version of Roberto Cavalli Men's Spring/Summer 2012 runway and opened the show held at the Palazzo Serbelloni in Milan.

His hobbies include watching films, reading books by Hermann Hesse, sunbathing, going to the mountains with friends, and listening to music.