[3] In the same year, he took clear first place in the Olomouc Open in Czech Republic with a score of 6½ points from 9 games;[4] thanks to this result, he also achieved his first norm required for the title Grandmaster (GM).

[5] Grandelius achieved the GM title by earning the third and final norm in the 40th Bosna International Tournament[6] in Sarajevo, in which he finished fifteenth, the first among juniors.

[12] In July 2015, he won the Swedish Chess Championship by defeating Emanuel Berg in a playoff match, after they both tied for first scoring 6½/9 points.

[13] The following month, Grandelius won the 22nd Abu Dhabi Masters tournament, edging out on tiebreak Martyn Kravtsiv, Baadur Jobava, Alexander Areshchenko and Richárd Rapport.

[14][15] In March 2016, Grandelius won a four-player tournament for the last place in the Norway Chess 2016 field, against Norwegian grandmasters Jon Ludvig Hammer and Aryan Tari, and Women's World Champion Hou Yifan.