The roIC gene, derived from Agrobacterium rhizogenes, has emerged as a powerful molecular tool for modifying phenotypic traits in horticultural crops. This article reviews the current understanding of RoIC -mediated phenotypic alterations across diverse ornamental and horticultural species. Research demonstrates that RoIC transformation consistently produces compact plant architectures characterized by reduced height, altered branching patterns, modified leaf and flower morphology, and changes in flowering time. These effects are mediated through alterations in plant hormone homeostasis, particularly involving cytokinin and auxin pathways. The severity of phenotypic changes correlates with RoIC expression levels and varies depending on the promoter used. Applications span major ornamental crops including petunia, carnation, rose, chrysanthemum, and various fruit crops, with significant implications for developing compact cultivars with improved horticultural characteristics. This review synthesizes findings from 30 key studies to provide a comprehensive understanding of RoIC gene function and its practical applications in ornamental plant breeding.