In 2005, Allamand made her first appearance in a film in Alberto Fuguet's film Se arrienda alongside Luciano Cruz-Coke. She became well known in Chile for her role as Eloísa Solé in Vivir con 10, a Chilevisión serial drama "Telenovela". She is also the brand ambassador for the Chilean Retail chain París.
Allamand would later appear in the Nicolás López trilogy "Qué pena tu vida" (2010), "Qué pena tu boda" (2011) and "Qué pena tu familia" (2013).
Her international film career began in 2013 with Aftershock, a Nicolás López film inspired by the 2010 earthquake in Concepción, Chile. The film was produced by Eli Roth, with whom she worked again on the 2013 horror film The Green Inferno and Knock Knock in 2015.