The　limited　mechanical　performance　and　responsiveness　of　protein-based　smart　packaging　materials　have　hindered　their　development.　To　address　these　issues,　this　study　prepared　a　pH-responsive　smart　film　by　introducing　dialdehyde　carboxylated　cellulose　nanofibers　(DCCNFs)　as　the　cross-linking　agent　capable　of　covalently　reacting　with　proteins,　and　bilberry　extract　(BE)　as　a　pH-responsive　indicator　into　pea　protein　isolate　(PPI)　matrix.　The　results　demonstrated　that　adding　DCCNF　and　BE　enhanced　the　PPI　film＇s　thermal　stability,　density,　and　UV　barrier　properties.　Tensile　tests　revealed　significant　improvements　in　both　tensile　strength　and　elongation　at　the　break　for　the　resulting　film.　Furthermore,　films　containing　DCCNF　and　BE　exhibited　lower　moisture　content,　swelling　ratio,　water　vapor　permeability,　and　relative　oxygen　transmission　compared　to　PPI　films.　Notably,　the　anthocyanins　in　BE　endowed　the　film　with　visual　color　changes　corresponding　to　different　pH　values.　This　feature　enabled　the　film　to　monitor　pork　freshness;　a　transition　from　acidic　to　alkaline　in　pork　samples　was　accompanied　by　a　color　change　from　brown　to　brownish　green　in　the　film　as　storage　time　increased.　Overall,　these　findings　highlight　that　this　developed　film　possesses　excellent　physicochemical　properties　and　sensitive　pH　response　capabilities,　making　it　a　promising　candidate　for　future　smart　packaging　applications.　©　2023　Elsevier　B.V.