Conventional dynamical decoupling employs pulse sequences whose microwave implementation relies on the rotating-wave approximation (RWA), which constrains the driving strength so that it remains much smaller than the qubit energy-level splitting. This requirement fundamentally limits pulse speed and detection bandwidth, particularly in systems with small level splittings. Here, we develop a Floquet-engineered dynamical decoupling framework that operates beyond the RWA and can simultaneously achieve high-fidelity decoupling, faster spin manipulation, and enhanced robustness under strong driving. Based on these pulses, we construct Floquet dynamical-decoupling sequences that maintain decoupling performance while substantially extending the detectable ac magnetic-field frequency range. Numerical simulations using nitrogen-vacancy centers demonstrate reliable quantum sensing in regimes inaccessible to conventional RWA-based schemes, with the detection bandwidth scaling directly with the achievable Rabi frequency. Our results establish Floquet-based dynamical decoupling as a general strategy for broadband quantum sensing in strongly driven two-level systems.

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• Quantum control
• Quantum metrology