Scalable superconducting quantum processors require balancing critical constraints in coherence, control complexity, and spectral crowding. Fixed-frequency architectures suppress flux noise and simplify control via all-microwave operations but remain limited by residual $ZZ$ crosstalk. Here we propose a microwave-activated three-qubit gate protocol for fixed-frequency transmon qubits in the large-detuning regime ($|\mathrm{\Delta }|\gg g$), leveraging the third-order nonlinear interaction to coherently exchange $|001⟩\leftrightarrow |110⟩$ states. By incorporating a phase-compensated optimization protocol, numerical simulations demonstrate a high average gate fidelity exceeding $99.9\mathrm{\%}$. Systematic error analysis identifies static long-range $ZZ$ coupling as the dominant error source in multiqubit systems, which can be suppressed via operations in the large-detuning regime (approximately $1$ GHz). The protocol maintains process fidelities exceeding 98% under decoherence, while demonstrating intrinsic robustness to fabrication-induced parameter variations and compatibility with existing all-microwave two-qubit gate architectures. This hardware-efficient strategy advances scalable quantum computing systems by improving coherence properties, reducing spectral congestion, and expanding the experimental toolkit for error-resilient quantum operations in the noisy intermediate-scale quantum era.

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• Quantum circuits
• Quantum control
• Quantum gates
• Quantum information with solid state qubits
• Quantum protocols
• Quantum state transfer
• Superconducting qubits
• Microwave techniques