Background Human immunodeficiency virus (HIV) screeners have limited experience of interacting with trans people. The application of communication platforms between them to empower HIV screeners’ trans-related cultural competence remains unknown. Objective This study aims to qualitatively explore the follow-up interviews of HIV screeners regarding their opinions on the feasibility of an online platform group discussion and web page to enhance communication between them and trans people and to explore their perspectives on how these components enhanced their promotion of cultural competence. Methods This study was conducted between October 2020 and June 2021. Purposive and snowball sampling were applied to recruit 6 trans persons and 11 HIV screeners. Six online platform group discussions were held on weekday evenings, each group meeting for 60 min, 360 min in total within 3 months, via a video chat room of Google Meet; this was supplemented by a closed web page. The major results were presented through content analysis of the HIV screeners’ follow-up interviews. Results The HIV screeners identified the facilitators of participating in the communication platforms, which included a reminder message, easy-to-use interface, visible–audible and readable interaction, recalled and reviewable content and group belonging; the barriers included time and space limitation, device restrictions and operation problem. Two categories of trans-related cultural competence – trans awareness and action taken – were revealed, from which five major themes emerged: provoked to ask questions, improved cognition, reflection, trans-sensitive communication and self-enhancement. Conclusion The results revealed that the communication platforms could facilitate the mutual and vivid discussion between HIV screeners and trans people and empower the trans-related cultural competence of HIV screeners. The highly feasible intervention design of this research can be applied to digital training courses related to gender diversity issues.