Rodents are born deaf and blind, and rely completely on their sense of smell for survival during the first two weeks of life. Despite being highly functional, the circuits that process odor inputs are structurally immature, and it remains unknown neonatal olfactory circuits reliably process information. We aimed to characterize olfactory circuit function by performing extracellular recordings and pharmacological manipulations in the olfactory bulb (OB) and piriform cortex (PCX) of unanesthetized rat pups ranging in age from several hours to three weeks after birth. We found that neonatal olfactory system exhibits highly structured and coherent odor-evoked oscillations (respiration-driven slow oscillations with nested 10-20 Hz spindle oscillations) that are reminiscent of adult beta oscillations. Oscillatory activity patterns remain stable during the first two weeks of life, after which they undergo rapid, quantitative changes to a mature state. Like adult beta oscillations, neonatal olfactory oscillations originate in the OB but are shaped by the PCX via net-inhibitory feedback projections that target granule cells. Finally, projection-specific optogenetic manipulations reveal that cortical feedback is sufficient to alter OB oscillatory activity. Thus, despite known structural changes at the cellular, molecular and synaptic levels, neonatal olfactory processing is characterized by highly stable network-level activity patterns that share characteristics with the adult olfactory system in terms of phenomenology and underlying circuitry.