In the context of bacteriophage (phage) therapy, there is an urgent need for a method permitting multiplexed, parallel phage susceptibility testing (PST) prior to the formulation of personalized phage cocktails for administration to patients suffering from antimicrobial-resistant bacterial infections. Methods based on surface plasmon resonance imaging (SPRi) and phase imaging were demonstrated as candidates for very rapid (<2 h) PST in the broth phase. Biosensing layers composed of arrays of phages 44AHJD, P68, and gh-1 were covalently immobilized on the surface of an SPRi prism and exposed to liquid culture of either Pseudomonas putida or methicillin-resistant Staphylococcus aureus (i.e., either the phages’ host or non-host bacteria). Monitoring of reflectivity reveals susceptibility of the challenge bacteria to the immobilized phage strains. Investigation of phase imaging of lytic replication of gh-1 demonstrates PST at the single-cell scale, without requiring phage immobilization. SPRi sensorgrams show that on-target regions increase in reflectivity more slowly, stabilizing later and to a lower level compared to off-target regions. Phage susceptibility can be revealed in as little as 30 min in both the SPRi and phase imaging methods.