The alpha subunit of the heterotrimeric G protein, G12, has been shown to modulate many cellular processes including cell‐to‐cell adhesion and oncogenic transformation. Among downstream effectors of G12 signaling, the Rho‐specific guanine nucleotide exchange factors (RhoGEFs) p115RhoGEF and leukemia‐associated RhoGEF (LARG) are of keen interest due to their ability to activate the monomeric G protein Rho, leading to an array of responses that include cell migration and transcriptional activation through serum response factor (SRF). The functional interaction between G12 proteins and RhoGEFs has been studied extensively; however, these studies have required the use of chimeric Gα proteins. In the present study, we have examined the interaction between a panel of engineered Gα12 mutants and immobilized forms of p115RhoGEF and LARG. We have identified several Gα12 mutants that are impaired in binding both RhoGEF proteins. Surprisingly, several mutations near the C‐terminus of Gα12 disrupt RhoGEF interaction and demonstrate a reduced ability to stimulate SRF mediated transcription. In conclusion, our findings implicate a previously unexamined region of Gα12 as critical for its interaction with RhoGEFs.