Born in Lautoka, Fiji to a Chilean father and Fijian mother, Montoya moved to Campbelltown, New South Wales at the age of three.
He played his junior rugby league for the Bankstown Bulls, and attended Patrician Brothers' College, Blacktown.
He plays for the Canterbury-Bankstown Bulldogs and played in their Harold Matthews Cup team. He progressed through the Bulldogs' youth system, and played in their NYC team between 2014 and 2016, scoring 36 tries in 46 matches. The captain of the NYC team in 2016, he also played seven games in the Bulldogs' New South Wales Cup team that year, scoring six tries.
Montoya's great form in the Holden Cup saw him promoted into the Bulldogs first grade NRL squad where he was on standby for the first grade team for the last few weeks of the season. On 8 October 2016, Montoya made his international debut for Fiji in an international against Samoa in Apia, playing on the wing and scoring a try in Fiji's 20–18 win.
In February 2017, Montoya was named in the Bulldogs 2017 NRL Auckland Nines squad. In round 3 of the 2017 NRL season, Montoya made his NRL debut for the Bulldogs against the New Zealand Warriors where he played on the wing and scored a try in the 24-12 win at Forsyth Barr Stadium in Dunedin, New Zealand. He is the first player of Chilean and South American descent to play in the NRL. He scored his first career double against the Newcastle Knights on the 7th of April 2017 in a 22 points to 12 win.
On 6 June, Montoya re-signed with the Canterbury-Bankstown Bulldogs for a further three seasons until the end of 2020. After a successful opening season in Montoya's career, the Canterbury-Bankstown Bulldogs named him the NRL Rookie of the year.
In 2018, Montoya made 15 appearances for Canterbury and scored 2 tries.