This study evaluated the effects of a new form of mobilization care called life-behavior-promotion care by comparing its effectiveness with that of conventional mobilization care, which promotes only walking. Methods: This was a quasi-experimental study that non-randomly allocated post-gastrointestinal surgery patients from a surgical ward into two groups: conventional care and life-behavior-promotion care. The participants received their respective care from ward nurses for the first 3 postoperative days and were asked to wear a pedometer and answer a self-administered questionnaire concerning these first 3 days. In addition, time to recover gastrointestinal function, time to completion of oxygen administration, and the number of days to achieve discharge criteria were collected from medical records. Results: Overall, 23 participants in the conventional-care group and 19 in the life-behavior-promotion-care group were analyzed. The latter group performed significantly more types of out-of-bed life behaviors during the 3 postoperative days. Among the questionnaire items concerning awareness of recovery, an interaction between intervention and length of postoperative days was confirmed for items reading "I was interested in surrounding events" and "I could spend a day like myself." In addition, in the life-behavior-promotion-care group, time to completion of oxygen administration was significantly shorter, and it took fewer days to achieve discharge criteria. Conclusions: The results of this study suggest that life-behavior-promotion care may promote out-of-bed life behaviors during the early postoperative period, and may improve mental and physical recovery in patients who have undergone gastrointestinal surgery. Clinical Trial Registration: The study was registered in the UMIN Clinical Trials Registry (trial ID: UMIN000021883).