Efficient genetic transformation has the potential to advance research and breeding in watermelon (Cit-rullus lanatus), but regeneration from tissue culture remains challenging. Previous work showed that expressing a fusion of two interacting transcription factors, GROWTH-REGULATING FACTOR4 (GRF4) and GRF-INTERACTING FACTOR1 (GIF1), improved regeneration in wheat (Triticum aestivum). By over-expressing a chimeric fusion of ClGRF4 and ClGIF1, we achieved highly efficient transformation in wa-termelon. Mutating the mi396 microRNA target site in ClGRF further boosted the transformation effi-ciency up to 67.27％ in a genotype-independent manner. ClGRF4-GIF1 can also be combined with clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) ge-nome editing tools to achieve highly efficient gene editing in watermelon, which we used to success-fully create diploid seedless watermelon. This re-search thus puts forward a powerful transformation tool for future watermelon research and breeding.