Egyptian chamomile is highly regarded in export markets. This study aimed to improve the essential oil yield and quality of four chamomile cultivars: Bode Gold, Zloty Lan, Local Improved, and Local. Treatments included gamma irradiation (5, 10, and 20 Gy) and foliar applications of colchicine and dimethyl sulfoxide (DMSO) at concentrations of 0.1, 0.2, and 0.4 ppm, conducted over two generations (M1 and M2, 2022–2024). Bode Gold demonstrated the highest essential oil percentage, attributed to superior vegetative and flowering traits, followed by Local Improved and Zloty Lan, with the Local cultivar yielding the least. Higher doses of gamma radiation (20 Gy) and elevated concentrations of colchicine and DMSO (0.4 ppm) significantly increased essential oil production in all cultivars compared to controls. Cross-pollination further enhanced yield, with Bode Gold contributing positively to other cultivars. Additionally, Bode Gold outperformed others in total essential oil components and mineral content. These results highlight the potential of advanced treatments and cross-pollination in enhancing chamomile oil productivity and quality, promoting diversification and competitiveness in global markets. Bode Gold emerges as a promising candidate for optimizing chamomile cultivation in Egypt.