Fabricating functional coordination polymer (CP) architectures and exploiting it as fluorescence sensors for detecting diverse metal ions and antibiotics, have attracted extensive attention. Based on a rarely-used benzimidazole-derived ligand 2,2′-bis-(2-pyridin-3-yl-vinyl)-3H,3′H-[5,5]bibenzoimidazole (L), a new CP {[Co(L)0.5(tbip)]·H2O}n (H2tbip =5‑tert-butylisophthalic acid) (1) was synthesized under solvothermal condition and characterized. Complex 1 reveals a two-dimensional network with the type of topology of 3,4,5L7. Complex 1 possesses excellent thermal and chemical stability. The fluorescence detection ability of complex 1 was explored and demonstrated that complex 1 can be used as the first fluorescent turn-on sensor to sense Al3+ and pefloxacin (PEF) with a low detection limit and fast response. The fluorescence enhancement mechanism was investigated in detail.