With the advancement of hepatopancreatobiliary surgery, the traditional treatment paradigm centered on anatomical resection and structural reconstruction is gradually evolving toward function-oriented decision-making. Increasing evidence indicates that achieving R₀ resection and anatomical patency alone is insufficient to optimize long-term outcomes, whereas postoperative loss of organ function, accompanied by metabolic disturbances, nutritional impairment, and reduced quality of life, has become a major determinant of long-term prognosis. Nevertheless, functional preservation poses distinct challenges across different organs. In liver surgery, discrepancies between residual liver volume and actual functional reserve limit the accuracy of current assessment systems. In pancreatic surgery, preservation of pancreatic function is intrinsically constrained by the increased risk of postoperative pancreatic fistula, creating a dilemma between short-term safety and long-term metabolic benefits. In biliary surgery, anatomical reconstruction does not necessarily ensure functional recovery, and increasing attention has been directed toward abnormalities in bile flow dynamics and biliary microbiota homeostasis. This review systematically summarizes the theoretical basis and clinical advances of organ function preservation in the liver, pancreas, and biliary system from the perspectives of functional assessment, surgical decision-making, and underlying biological mechanisms. It further proposes several function-oriented concepts, including the "territory-function balance" in liver surgery, the "function-risk trade-off" in pancreatic surgery, and the "functional safety window" in biliary surgery. Future progress in hepatopancreatobiliary surgery is expected to shift from the pursuit of anatomical success alone toward the establishment of function-oriented decision-making systems, aiming to achieve optimal organ function, metabolic homeostasis, and quality of life while maintaining oncological safety.