This volume contains the proceedings of the 1st Workshop on StyGenAI 2026, co-located with the 27th Annual Conference of the EAMT 2026. StyGenAI is the first workshop dedicated specifically to the study of style in Generative AI-translated content. The workshop welcomed empirical, methodological, and conceptual contributions examining stylistic regularities, deviations, and innovations in AI-generated translation. Particular attention was given to questions of genre, language pair, prompting strategies, evaluation methodologies, and human-AI interaction in translation workflows. The workshop provided a forum for researchers and practitioners interested in understanding how large language models shape translated texts, how their outputs differ from both human translation and traditional machine translation systems, and how stylistic patterns emerge, stabilise, or drift across genres, languages, and translation settings. The accepted papers reflect the diversity of approaches currently being developed to investigate style in GenAI-mediated translation.