Can I put a box spring under a hybrid mattress?

Yes, you can put a box spring under a hybrid mattress, but a solid or slatted platform is usually a better match for how hybrid mattresses are built.

Hybrid mattresses combine pocketed coils with foam layers, and that coil system already handles much of the flex and pressure distribution a traditional box spring was designed to provide. A solid-top box spring works fine and won't void most warranties, but an old-style spring box spring adds unnecessary bounce and can accelerate coil wear over time. Slat spacing matters too: gaps wider than 3 inches let the hybrid mattress sag between supports.

Hybrid mattress coil layers perform best on a firm, flat surface with slat gaps no wider than 3 inches.
A solid-top (non-spring) box spring is compatible with most hybrid mattresses without affecting warranty coverage.
Traditional spring box springs add extra flex that can accelerate wear on a hybrid mattress's pocketed coil system.
Most hybrid mattress warranties require a center support beam for queen and king sizes, regardless of foundation type.