H ow Ca²⁺-dependent signaling effectors are regulated in cardiomyocytes, given the extreme cytoplasmic Ca²⁺ concentration changes that underlie contraction, remains unknown. Cardiomyocyte plasma membrane Ca²⁺-ATPase (PMCA) extrudes Ca²⁺ but has little effect on excitation-contraction coupling, suggesting its potential role in controlling Ca²⁺-dependent signaling effectors such as calcineurin. We generated cardiac-specific inducible PMCA4b transgenic mice that displayed normal global Ca²⁺ transient and cellular contraction levels and reduced cardiac hypertrophy following transverse aortic constriction (TAC) or phenylephrine/Ang II infusion, but showed no reduction in exercise-induced hypertrophy. Transgenic mice were protected from decompensation and fibrosis following long-term TAC. The PMCA4b transgene reduced the hypertrophic augmentation associated with transient receptor potential canonical 3 channel overexpression, but not that associated with activated calcineurin. Furthermore, Pmca4 gene–targeted mice showed increased cardiac hypertrophy and heart failure events after TAC. Physical associations between PMCA4b and calcineurin were enhanced by TAC and by agonist stimulation of cultured neonatal cardiomyocytes. PMCA4b reduced calcineurin nuclear factor of activated T cell–luciferase activity after TAC and in cultured neonatal cardiomyocytes after agonist stimulation. PMCA4b overexpression inhibited cultured cardiomyocyte hypertrophy following agonist stimulation, but much less so in a Ca²⁺ pumping–deficient PMCA4b mutant. Thus, Pmca4b likely reduces the local Ca²⁺ signals involved in reactive cardiomyocyte hypertrophy via calcineurin regulation.