Quinolinic acid (QA) is an index for some diseases, whose detection is of importance. This work presents a samarium metal–organic framework (Sm-MOF) containing 5-sulfoisophthalate ligand (SIP3–). The fluorescence of Sm-MOF integrates the emission at 339 nm from the SIP3– ligand and four characteristic 4G5/2 → 4H j (j = 5/2, 7/2, 9/2, and 11/2) transitions at 559, 596, 642, and 701 nm from Sm(III). Sm-MOF as a turn-off fluorescence sensor to QA exhibits high sensitivity, selectivity, and durability. The fluorescence quenching response to QA shows a linear relationship of I 0/I = 0.00496·C QA + 1.12474 in the QA concentration of 0–500 μM and a limit of detection calculated as 4.11 μM. Sm-MOF shows the structural and fluorescent stabilities in five quenching–recovery cycles. The recoveries of close to 100% in human urine and serum indicate high reliability. The paper-based Sm-MOF sensor displays a rough QA quantitative analysis by recognizing red values in the on-site QA detection.