In round 8 of the 2013 NRL season, Terepo made his NRL debut for the Parramatta Eels against the North Queensland Cowboys at in the Eels 10–14 loss at Parramatta Stadium. In round 10, against the St George Illawarra Dragons, Terepo scored his first and second try NRL career tries in the Eels 12–32 loss at WIN Stadium. On 5 July 2013, Terepo extended his contract with the Eels for a further 2 years until the end of the 2015 season. Terepo finished his debut year in the NRL with him playing in 17 matches and scoring 4 tries for the Parramatta Eels in the season. Terepo was included in the Tongan squad for the 2013 Rugby League World Cup, playing in one match and scoring a try against Italy in the 16–0 win at The Shay.