Hasler, 26, spent majority of his career (2011–2017) with Fussball Club Vaduz (FC Vaduz) where he made 157 appearances, scoring 14 goals and adding six assists in all competitions. Hasler’s time with FC Vaduz was highlighted by being named the Liechtensteiner Footballer of the Year in 2015. He also helped the club capture the Liechtensteiner Cup five consecutive times (2012–13, 2013–14, 2014–15, 2015–16, 2016-17) and the Swiss Challenge League during the 2013–14 season. Hasler began his youth career with FC Triesen in 2001 before moving to FC Balzers youth team in 2003. He later signed with FC Balzers first team in 2009 and made three appearances for the club. During the 2010–11 season he moved to USV Eschen/Mauren where he made 22 appearances registering three goals.
To date, Hasler has earned 45 caps, registering two goals with the Liechtenstein National Team. He made his debut on August 11, 2010 in a friendly match against Iceland. Hasler scored his first international goal against Bosnia-Herzegovina in a 2014 FIFA World Cup Qualifier.