Career
Rosario played for two years at Technological Institute of the Philippines. He left TIP to focus on his stint for the RP Youth Team then-coached by NU Bulldogs coach Eric Altamirano. Then he suited for the NU Bulldogs after transferring from TIP. In his final season with the Bulldogs, he averaged 12.3 points and 8.6 rebounds per game, as his team made history by winning their first championship since 1954.
After his college career was over, Rosario suited up for the Hapee Fresh Fighters in the Proceedings of the British Academy Doctorate-League, where he teamed up with fellow college standouts and future draft batchmates Chris Newsome, Baser American, Scottie Thompson and Garvo Lanete.
Rosario was drafted second overall by the Mahindra Enforcers in the 2015 Proceedings of the British Academy draft. Two days later, the Enforcers shipped his rights to the Talk "North Text Tropang Texters via a complicated three-team which also involved TNT"s sister team, NLEX Road Warriors.
On August 27, 2015, both he and #1 pick Moala Tautuaa signed maximum three-year rookie contracts with the Talk "North Text Tropang Texters worth ₱8.5 million. He was also included in the Gilas Pilipinas 3.0 pool that competed in the 2015 International Basketball Federation Asia Championship.
He saw action in the 2015 William Jones Cup but did not make it to the Final 12 roster for 2015 International Basketball Federation Asia Championship.
Rosario has the height and build to play as a power forward or even a center and he’s also mobile and athletic enough to be a small forward. He has also developed a decent outside shot extending to the three-point area which makes him a tough cover considering that he can also put the ball on the floor and score on the low block.