Abstract We highlight the recent advance in strong transformation-induced plasticity (TRIP) steels, which have higher alloying contents compared to the conventional TRIP steels for achieving tensile strength higher than 1 GPa. Given that the extraordinary strength-elongation balance is led by the characteristic mixture of coarse and submicron-sized grains of ferrite and austenite, diverse strategies of materials design to obtain unprecedented properties are reviewed. Challenges to achieve the vital engineering parameters other than tensile properties are discussed as well, which should be resolved to secure competitiveness over other emerging structural alternatives.