Born in the Auckland suburb Titirangi, Hassett began playing football at the age of four with her brothers. She was captain of Avondale College First XI Girls Football team in 2008 and led them to third place at the National Schools Tournament.
Hassett attended the University of California, Berkeley where she played for the California Golden Bears from 2009 to 2012. Due to injuries, Hassett had limited playing time in her first year but in her second year she played in 15 games, starting 11 and was the sole Bear on the Pac-10 all-academic second team. During her junior year, she played in all 22 matches with 18 starts in the midfield. She was a Second-Team All-Pac-12 selection and Third Team NSCAA Scholar All-American. She was also named to the 2011 Pac-12 All-Academic team. As a senior, Hassett started in nineteen of the twenty regular season games. From her central mid-field position she scored 6 goals and assisted on 5 goals. She was one of only two California players earning highest All Pac-12 honours by being named to the All-Pac-12 First Team.
Playing career
Club
Hassett signed for German second tier side SC Sand in 2013. She scored 11 goals in her 10 appearances for the club during the 2012–13 season. SC Sand finished in third place during the regular season with a record. In 2014, Hassett signed for Manchester City in England. Of her signing, she said, "I like the idea of being part of a side that's entering the FA WSL for the first time. This way we can start from scratch with a new style and I can play to my strengths rather than trying to adapt to an already existing and established environment." Hassett started in 11 of the 13 matches in which she played. Manchester finished its inaugural season in the FA Women's Super League in fifth place with a record. Hassett played for Norwegian Toppserien club Amazon Grimstad during the 2015 season. The club was facing the threat of relegation as the last place team in the league. Hassett made 11 appearances for the club and scored a goal in the team's 2–0 win over Medkila. The team finished in last place with a record. After signing with SV Werder Bremen in the German Frauen-Bundesliga for the 2015–16 season, Hassett made 8 starts in her 10 appearances for the club. During a match against SC Freiburg on March 20, 2016, she scored the game-winning goal. The club finished in 11th place with a record. In July 2016, Hassett transferred to Ajax in the Netherlands' Eredivisie for the 2016–17 season. Ajax finished in first place during the regular season with a record 15 points ahead of the second place team. After winning the championship, Ajax secured a spot in the 2017–18 UEFA Women's Champions League, a first for the club.
Hassett made her senior Football Ferns debut in a 1–0 win over Argentina on 16 June 2008. She played in Germany at the 2011 FIFA Women's World Cup with New Zealand, seeing time in all three games. In 2012, she represented her country at the London Olympics, helping the Football Ferns become the first New Zealand team to advance to the second round in a major FIFA tournament. She played in all four games with three starts. Hassett featured in all three of New Zealand's matches at the 2015 FIFA Women's World Cup in Canada. She also featured in all three of New Zealand's matches at the 2016 Olympics.
