Peroxisomes carry out a diverse set of metabolic functions, including oxidation of very long-chain fatty acids, degradation of D-amino acids and hydrogen peroxide, and bile acid production. Many of these functions are upregulated on demand; therefore, cells control peroxisome abundance, and by extension peroxisome function, in response to environmental and developmental cues. The mechanisms upregulating peroxisomes in mammalian cells have remained unclear. Here, we identify a signaling regulatory network that coordinates cellular demand for peroxisomes and peroxisome abundance by regulating peroxisome proliferation and interaction with ER. We show that PKC promotes peroxisome PEX11b-dependent formation. PKC activation leads to an increase in peroxisome-ER contact site formation through inactivation of GSK3β. We show that removal of VAPA and VAPB impairs peroxisome biogenesis and PKC regulation. During neuronal differentiation, active PKC leads to a significant increase in peroxisome formation. We propose that peroxisomal regulation by transient PKC activation enables fine-tuned responses to the need for peroxisomal activity.