Indigenous predatory BALO strains were successfully isolated from activated sludge. Sludge SRF and CST were significantly reduced by BALOs induced biolysis process. The increase of BALO input dosage promoted the sludge biolysis efficiency. Sludge biolysis disintegrated flocs and lysed cells for internal water release. The optimal sludge biolysis time was 24 h and no pH adjustment was needed. -and-like organisms (BALOs) are a group of ubiquitous and obligate predatory bacteria and commonly used as biocontrol agents. In this study, an efficient, environmental-friendly, and convenient BALOs encouraged municipal waste sludge biolysis pretreatment technique was developed and investigated for dewaterability enhancement of excess waste sludge. The indigenous predatory BALOs were successfully isolated from the sludge for biolysis treatment. Without any chemical addition or pH adjustment, the sludge specific resistance (SRF) and capillary suction time (CST) were significantly reduced by as high as 53.4% and 23.8%, respectively within 24 h’s treatment, which would further be lowered with the increase of BALOs input dosage. However, the continuous extension of reaction time would worsen the sludge dewaterability. The decreases of SRF and CST accompanied with the increases of sludge disintegration degree and soluble chemical oxygen demand, nitrogen, and phosphorus concentrations all emphasized the contributions of BALOs’ predation activities to sludge disturbance, cell lysis, and consequently the release of sludge intracellular water to finally effectively improve the sludge dewaterability and disposal efficiency.