<p>Plant architecture is a major factor affecting crop management and yield. The erect leaf phenotype is a key trait for improving light capture, reducing water loss, optimizing space utilization, and facilitating the chemical and biological control of arthropods and pathogens, especially those infesting/infecting abaxial leaf surfaces. This phenotype has been associated with <i>Tiller Angle Control 1</i> (<i>TAC1</i>)-like genes across many herbaceous and tree species. Our previous genomic and genetic analyses of the erect leaf phenotype in tomato (<i>Solanum lycopersicum</i>) indicated that this trait is controlled by a semi-dominant locus, <i>Erl</i>, on chromosome 10. We discovered that this phenotype was in tight linkage with a candidate loss-of-function mutation in <i>Solyc10g009320</i>, an ortholog of <i>TAC1</i>-like genes. Therefore, editing this gene might confirm its function and enable the fine-tuned manipulation of aboveground tomato plant architecture. Here, we utilized a CRISPR/Cas9 genome editing system to confirm the complete genetic association of the erect leaf phenotype in tomato by knocking out <i>Solyc10g009320</i> in tomato cultivar ‘Micro-Tom’. In addition, we analyzed the effects of editing this gene on the overall plant phenotype as well as physiological and agronomic performance. Editing <i>Solyc10g009320</i> alleles in tomato lays the foundation for the large-scale generation of superior genotypes, paving the way for the development of elite cultivars with an erect leaf phenotype.</p>