The development of metal–organic framework (MOF) materials with multifunctionalities has boosted their prospects in the fields of spintronics and optoelectronics. However, incorporating magnetic and optoelectronic properties in MOF materials remains challenging. Herein, the in situ synthesis of Cu-MOF-74, a typical one-dimensional linear magnet, is systematically investigated, which shows ferromagnetic and antiferromagnetic interactions along the axial chain direction, and overall tilted antiferromagnetism at low temperatures. In particular, the introduction of SnS:Co quantum dots (QDs) enhances the antiferromagnetic coupling, which increases the phase transition temperature of the MOF from 7.8 K to 275 K at 1000 Oe. In addition, it is demonstrated that Cu-MOF-74 possesses both magnetic and optoelectronic properties. It is found that the responsivity and detectivity of the Cu-MOF-74 photodetector are both significantly improved by the SnS:Co QDs. This research provides promising methods for concurrent improvement of the magnetic and optoelectronic properties of MOF materials, advancing in-depth research on the MOF film as a new type of semiconductor for spintronic and optoelectronic devices.