In the human fungal pathogen Candida albicans, invasive hyphal growth is a well-recognized virulence trait. We employed transposon-mediated genome-wide mutagenesis, revealing that inactivating CTM1 blocks hyphal growth. CTM1 encodes a lysine (K) methyltransferase, which trimethylates cytochrome c (Cyc1) at K79. Mutants lacking CTM1 or expressing cyc1K79A grow as yeast under hyphae-inducing conditions, indicating that unmethylated Cyc1 suppresses hyphal growth. Transcriptomic analyses detected increased levels of the hyphal repressor NRG1 and decreased levels of hyphae-specific genes in ctm1Δ/Δ and cyc1K79A mutants, suggesting cyclic AMP (cAMP)-protein kinase A (PKA) signaling suppression. Co-immunoprecipitation and in vitro kinase assays demonstrated that unmethylated Cyc1 inhibits PKA kinase activity. Surprisingly, hyphae-defective ctm1Δ/Δ and cyc1K79A mutants remain virulent in mice due to accelerated proliferation. Our results unveil a critical role for cytochrome c in maintaining the virulence of C. albicans by orchestrating proliferation, growth mode, and metabolism. Importantly, this study identifies a biological function for lysine methylation on cytochrome c. Display omitted •The methyltransferase Ctm1 is essential for the hyphal growth of Candida albicans•Ctm1 specifically catalyzes the trimethylation of cytochrome c (Cyc1) at lysine 79•Unmethylated Cyc1 binds to the catalytic subunits of PKA and inhibits their kinase activity•ctm1Δ/Δ mutant retains virulence in mice by improving proliferation via metabolic adaptation Through a transposon-mediated genetic screen, Zeng et al. identify the methyltransferase Ctm1 as a critical regulator of hyphal growth. Ctm1 specifically methylates cytochrome c (Cyc1) at lysine 79. Unmethylated Cyc1 binds to the catalytic subunits of protein kinase A and inhibits their activity, blocking cAMP-PKA signaling and hyphal development.