Montiel had youth spells with IK Franke and Västerås SK, he made his first-team debut with the latter on 7 July 2012 in a Division 1 Norra match against Östersund. In 2013, Montiel joined Allsvenskan club IF Brommapojkarna. He was named on the substitutes bench twice for the club's 2014–15 UEFA Europa League first qualifying round ties against VPS. After not appearing for the club's senior team he left and rejoined Västerås SK in 2014. He went onto score three goals in thirteen fixtures during the 2014 Division 1 season. In January 2015, Montiel completed a transfer to fellow Division 1 Norra team Dalkurd FF. He participated in twenty-four games in his debut season with them as they won promotion to the 2016 Superettan. On 11 November 2016, it was announced that Montiel had agreed to sign for Allsvenskan side IK Sirius on a three-year contract and would officially join on 1 January 2017. He made his debut for IK Sirius in a Svenska Cupen match versus Arameisk-Syrianska IF and scored the fifth goal in a 0–5 win. On 28 July, Montiel joined Superettan side Gefle IFon loan. He scored his first Gefle goal in his second match, on 6 August, against IFK Värnamo. In total, Montiel scored two goals in fourteen matches for Gefle as they finished 12th. He terminated his contract with Sirius in November 2017. On 5 December, Montiel agreed to join Superettan club Örgryte IS. In his opening six matches, Montiel scored five goals and assisted four. He ended the 2018 campaign as top scorer, netting thirteen goals alongside fourteen assists in twenty-eight appearances. He departed at the conclusion of his contract in December. At the end of the month, Montiel secured a move to Beerschot Wilrijk of the Belgian First Division B. In July 2019, Beerschot allowed Montiel to speak to a Swedish club with a view to a transfer. Västerås SK revealed he was training with them on 8 July. On 15 July 2019, Vejle BK confirmed that they had signed Montiel on a two-year contract. He scored twice, versus Nykøbing and Vendsyssel FF, in his first three appearances for Vejle BK.
International career
Montiel, who is of Uruguayan descent, has represented Sweden at U17 level, debuting in a friendly tournament match against Iceland U17 in July 2014. His next cap came later that month in the same competition against Romania U17.
