Purpose <p>This study tested the feasibility and preliminary efficacy of an artificial intelligence (AI)-based survivorship care plan (SCP) service (named “quality of life [QOL] + intervention”) for posttreatment breast cancer survivors using digital platforms.</p> Methods <p>A single-arm prospective pilot study was conducted, and 38 posttreatment breast cancer survivors in South Korea were enrolled. The QOL + intervention consisted of 1) collection of patient-reported outcomes data from survivors via a mobile app, 2) automated generation of SCP via a website, and 3) in-person SCP review and counseling. Feasibility was assessed using study participation rate, retention rate, mobile app access rate, task completion rate, intervention satisfaction, etc. Preliminary efficacy was evaluated using changes in patient-provider interaction, patient activation, cancer survivors’ self-efficacy, and QOL from baseline to 1&#xa0;week after the intervention.</p> Results <p>Feasibility assessment showed promising results, with a 70.7% participation rate, an 89.5% retention rate, an 88.2% mobile app access rate, a 91.2% task completion rate, and an 88.2% satisfaction rate. The QOL + intervention improved patient activation (<i>p</i> = 0.051, effect size = 0.29), self-efficacy (<i>p</i> = 0.040, effect size = 0.31), and QOL (<i>p</i> = 0.010, effect size = 0.42). However, no significant change occurred in patient-provider interaction after the intervention (<i>p</i> = 0.098).</p> Conclusions <p>The QOL + intervention was feasible and preliminarily effective in improving patient outcomes among posttreatment breast cancer survivors in South Korea. To obtain robust evidence, large-scale randomized controlled trials are warranted in future studies.</p> Implications for Cancer Survivors <p>Survivorship care can be enhanced via AI-based digital technology.</p> <p><b>Trial registration</b>&#xa0;KCT0009302.</p>