The Danes won the final 17-21, 21-12, 21-12 against Yuichi Shimogami and Sayaka Hobara to celebrate their sixth tournament win within just one year.
The fifth-seeded Danes were clear favorites in the final against the Japanese surprise duo, and after struggling in the first set, they turned the tide in the second and third sets to complete their triumph.
The triumph is 32-year-old Christiansen and 26-year-old Boje's second at the Super 750 level after they won the same tournament in 2023.
In total, they have been part of 15 finals on the BWF World Tour and two European Championship finals, winning ten of them. They have secured five titles on the BWF World Tour and a European Championship final in the past ten months.
For the same reason reason, Boje and Christiansen will be among the favorites when they take part in the Super 1000 tournament, the Indonesia Open next week.
In an arena with open doors and air conditioning, wind has played a role all week in Singapore, and that was also the case in Sunday's final.
The Danes played the first set on the least advantageous side, and after an even opening, the set tipped in favour of the Japanese.
Boje and Christiansen fell behind 9-14, but responded well and restored parity at 15-15, before Shimogami and Hobara ran away with the set decisively.
In the second set, the Danes took a 9-2 lead, and despite a few Danish errors, Boje and Christiansen took the second set with ease.
The Danes then took an 11-7 lead in the third set, even though they started on the bad side, and therefore, there was no real tension about the outcome in the last part of the match, where the Danish pair put the icing on the cake of a very solid performance.