On 6 February 2009, Molloy made her debut for the Ireland women's national rugby union team when she came on as replacement in a 7–5 win against France. This was the first time the Ireland Women had beaten France. Molloy went onto represent Ireland at the 2010, 2014 and 2017 Women's Rugby World Cups. At the 2014 tournament she was a member of the Ireland team that defeated New Zealand. She captained the Ireland team at the 2017 tournament, replacing an injured Niamh Briggs. Molloy was also a member of the Ireland teams that won the 2013 and 2015 Women's Six Nations Championships.