The rising global population and increasing food security challenges necessitate the rapid development of high-yield and stress-resilient crops. Compared to conventional breeding that rely on multiple generations of self-crossing, doubled haploid technology can significantly accelerate this timeline. Therefore, identifying efficient and broadly applicable haploid inducers is essential for accelerating crop improvement. Here, our work identifies GEX3 as a conserved and reliable haploid inducer across both monocot and dicot lineages, including Arabidopsis, rice, tomato, and soybean. These findings establish GEX3 as a conserved, sperm-specific factor essential for gamete fusion and genomic transmission, thereby positioning it as a broadly applicable target for advancing in vivo doubled haploid technologies in diverse crops.