Water contamination is a highly critical issue owing to its strong relationship to human health. In addition to chemical pollutants, microorganisms such as multiresistant pathogenic bacteria have received significant attention from the World Health Organization. The main problem associated with monitoring pathogenic bacteria in water is the interference from concomitant species and their low concentrations. To address this problem, we synthesized a bilanthanide-organic material as an efficient luminescence sensor for the detection of Pseudomonas aeruginosa, a representative bacterium, via its two unique biomarkers: 1-hydroxyphenazine (1-HX) and 2-aminoacetophenone (2-AA). This multiplexed sensing approach overcomes a common issue encountered by single-marker luminescence sensors that may report false positives due to coexisting species in the complex environment. High sensitivities and low limits of detection for 1-HX and 2-AA were obtained with very fast response time. The key structural factors governing the high-performance sensing function were revealed. This work provides an alternative route for the effortless and instant detection of bacterial biomarkers in water.