Objective To investigate the clinical application value of a digital check-in program-based ankle pump exercise intervention protocol in enhancing lower limb hemodynamics, improving exercise compliance, and preventing thrombosis in elderly gastrointestinal cancer patients at high risk of venous thromboembolism. Methods A prospective study design was adopted. From May 1 to December 31, 2024, 60 elderly gastrointestinal cancer patients with a Padua score ≥4 admitted to the Department of Geriatrics of Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, were selected as the study subjects. Using a consecutive sampling method, they were divided into a control group and an experimental group, with 30 cases in each group. Both groups received a 14-day intervention. The control group performed self-guided ankle pump exercises under routine health education instruction, while the experimental group received a standardized and supervised ankle pump exercise intervention via a self-developed digital exercise check-in program. At pre-intervention (baseline) and on day 1, 7, and 14 of the intervention, color Doppler ultrasound was used to measure and compare the popliteal vein diameter and peak flow velocity between the two groups. The implementation rate and standard fulfillment rate of ankle pump exercises, along with patient compliance were recorded and analyzed. The incidence of deep vein thrombosis was also monitored in both groups. Results By day 14, the popliteal vein diameter in the experimental group [(7.10±1.31) mm] was significantly larger than that in the control group [(6.47±1.06) mm] (P<0.05), though no significant differences were observed at baseline or on day 1 and 7. Popliteal vein flow velocity showed significant main effect of time (F for time=21.999, P<0.001) and time-group interaction effect (F for interaction=92.402, P<0.001). Between-group comparisons showed that on day 7 and 14, the popliteal vein flow velocity in the experimental group [(7.78±1.03) cm/s and (8.25±1.08) cm/s] was significantly higher than that in the control group [(7.04±1.29) cm/s and (6.93±1.25) cm/s] (both P<0.05). On day 14 of the intervention, the implementation rate of ankle pump exercises in the experimental group (100.0%) and the movement standard fulfillment rate (96.7%) were both significantly higher than those in the control group (P<0.05). During the intervention, no deep vein thrombosis occurred in the experimental group, while 2 cases (6.7%) were observed in the control group, with no statistically significant between-group difference (P=0.492). Conclusions As a structured and monitorable intervention tool, the digital ankle pump exercise check-in program can effectively promote popliteal venous dilation and blood flow acceleration in elderly gastrointestinal cancer patients at high risk of thrombosis. It also significantly improves the standardized implementation rate and long-term compliance with ankle pump exercises. This intervention demonstrates positive clinical significance in preventing lower limb deep vein thrombosis and provides an operable digital solution for the standardized physical prophylaxis of venous thromboembolism in cancer patients.