The three‐dimensional metal–organic framework Gd (HCOO) 3 is characterized by a relatively compact crystal lattice of weakly interacting Gd 3+ spin centers interconnected via lightweight formate ligands, overall providing a remarkably large magnetic: non‐magnetic elemental weight ratio. The resulting magnetocaloric effect per unit volume is decidedly superior in Gd (HCOO) 3 than in the best known magnetic refrigerant materials for liquid‐helium temperatures and low‐moderate applied fields.