In　this　paper,　the　state　estimator　design　problem　of　interval　type-2　Takagi–Sugeno　fuzzy　systems　suffering　from　bounded　disturbances　is　studied.　To　enhance　the　resilience　of　the　estimator,　a　non-fragile　design　scheme　is　proposed　to　tackle　the　estimator　gain　variations.　Meanwhile,　an　event-triggered　communication　mechanism　is　introduced　for　relieving　the　transmission　burden　over　networks.　To　settle　down　the　non-fragile　estimator　design　issue　subject　to　bounded　disturbances　and　event-induced　error,　we　propose　a　new　definition　of　quadratic　boundedness　via　the　multiple　Lyapunov　functions.　Based　on　this　definition,　a　novel　co-design　method　of　estimator　and　event　generator　for　fuzzy　system　models　in　the　presence　of　both　measurable　and　immeasurable　premise　variables　is　presented.　In　virtue　of　quadratic　boundedness　framework,　less　conservative　conditions　of　the　existence　and　quadratic　stability　of　the　fuzzy　estimators　are　obtained,　and　the　upper　bound　of　estimation　error　is　given　explicitly.　The　desired　estimator　gains　are　determined　by　convex　optimization　technique　using　slack　matrices.　Two　illustrative　examples　are　exploited　to　validate　the　availability　and　superiority　of　the　addressed　design　approach.　©　2023　Elsevier　Ltd