Abstract <p>We investigate the frustrated Shastry–Sutherland–Kondo lattice model using the variational cluster approximation to study the competition among antiferromagnetism, Kondo screening, and geometric frustration. The model incorporates electron hopping, Coulomb correlations, Kondo exchange, and diagonal frustrating interactions, providing a unified framework for competing magnetic and singlet phases. By exploring the ground-state phase diagram in the (<i>J</i>/<i>t</i>,&#xa0;<i>U</i>/<i>t</i>), <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\((J/t,J_K/t)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mi>J</mi> <mo stretchy="false">/</mo> <mi>t</mi> <mo>,</mo> <msub> <mi>J</mi> <mi>K</mi> </msub> <mo stretchy="false">/</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation>, and <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\((J/t,t'/t)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mi>J</mi> <mo stretchy="false">/</mo> <mi>t</mi> <mo>,</mo> <msup> <mi>t</mi> <mo>′</mo> </msup> <mo stretchy="false">/</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> parameter spaces, we show that long-range Néel order is stabilized at weak Kondo coupling, while stronger Kondo screening suppresses magnetism in favor of a Kondo singlet phase. Increasing frustration strongly reduces the antiferromagnetic region and promotes nonmagnetic singlet states. Our results reveal a substantial modification of the conventional Doniach scenario, where frustration introduces an additional mechanism for singlet formation, highlighting the cooperative roles of correlations, Kondo physics, and lattice geometry in frustrated quantum materials.</p> Graphical abstract <p></p>