diff --git a/.changes/20260708_140000_cardano-api_pablo.lamela_nonthrowing_utf8_decode.yml b/.changes/20260708_140000_cardano-api_pablo.lamela_nonthrowing_utf8_decode.yml
new file mode 100644
index 0000000000..ed0f28f5d0
--- /dev/null
+++ b/.changes/20260708_140000_cardano-api_pablo.lamela_nonthrowing_utf8_decode.yml
@@ -0,0 +1,6 @@
+description: |
+  Fixed `deserialiseInput`, `deserialiseInputAnyOf` and `deserialiseAnyVerificationKeyBech32` (and thereby `deserialiseAnyVerificationKey`) to return an error instead of throwing an impure exception when the input is not valid UTF-8. Added a `Bech32InvalidUtf8` constructor to `Bech32DecodeError`, which carries the rendered UTF-8 decoding error.
+kind:
+- bugfix
+pr: 1249
+project: cardano-api
diff --git a/cardano-api/src/Cardano/Api/Key/Internal/SomeAddressVerificationKey.hs b/cardano-api/src/Cardano/Api/Key/Internal/SomeAddressVerificationKey.hs
index 1d7fa9ebef..b6ccbd64eb 100644
--- a/cardano-api/src/Cardano/Api/Key/Internal/SomeAddressVerificationKey.hs
+++ b/cardano-api/src/Cardano/Api/Key/Internal/SomeAddressVerificationKey.hs
@@ -28,10 +28,12 @@ import Cardano.Api.Serialise.TextEnvelope.Internal
 import Cardano.Chain.Common qualified as Common
 import Cardano.Crypto.Signing qualified as Crypto
 
+import Control.Exception (displayException)
 import Data.Aeson qualified as Aeson
 import Data.Bifunctor (first)
 import Data.ByteString (ByteString)
 import Data.Text (Text)
+import Data.Text qualified as Text
 import Data.Text.Encoding qualified as Text
 import Formatting (build, sformat, (%))
 
@@ -142,8 +144,11 @@ deserialiseAnyVerificationKey bs =
 
 deserialiseAnyVerificationKeyBech32
   :: ByteString -> Either Bech32DecodeError SomeAddressVerificationKey
-deserialiseAnyVerificationKeyBech32 =
-  deserialiseAnyOfFromBech32 allBech32VerKey . Text.decodeUtf8
+deserialiseAnyVerificationKeyBech32 bs =
+  case Text.decodeUtf8' bs of
+    -- The input is not valid UTF-8, so it cannot be valid Bech32.
+    Left err -> Left $ Bech32InvalidUtf8 $ Text.pack $ displayException err
+    Right text -> deserialiseAnyOfFromBech32 allBech32VerKey text
  where
   allBech32VerKey
     :: [FromSomeType SerialiseAsBech32 SomeAddressVerificationKey]
diff --git a/cardano-api/src/Cardano/Api/Serialise/Bech32.hs b/cardano-api/src/Cardano/Api/Serialise/Bech32.hs
index 6fa1840434..c4633bb847 100644
--- a/cardano-api/src/Cardano/Api/Serialise/Bech32.hs
+++ b/cardano-api/src/Cardano/Api/Serialise/Bech32.hs
@@ -149,6 +149,9 @@ data Bech32DecodeError
       -- ^ Expected header
       !Text
       -- ^ Unexpected header
+  | -- | The input is not valid UTF-8, so it cannot be a Bech32-encoded
+    -- string. The field contains the rendered UTF-8 decoding error.
+    Bech32InvalidUtf8 !Text
   deriving (Eq, Show, Data)
 
 instance Error Bech32DecodeError where
@@ -181,3 +184,5 @@ instance Error Bech32DecodeError where
         [ "Unexpected CIP-129 Bech32 header: the actual header is " <> pshow actual
         , ", but it was expected to be " <> pshow expected
         ]
+    Bech32InvalidUtf8 decodeErr ->
+      "The Bech32-encoded string is not valid UTF-8: " <> pretty decodeErr
diff --git a/cardano-api/src/Cardano/Api/Serialise/DeserialiseAnyOf.hs b/cardano-api/src/Cardano/Api/Serialise/DeserialiseAnyOf.hs
index 6fce35def4..abbc738907 100644
--- a/cardano-api/src/Cardano/Api/Serialise/DeserialiseAnyOf.hs
+++ b/cardano-api/src/Cardano/Api/Serialise/DeserialiseAnyOf.hs
@@ -35,7 +35,6 @@ import Data.ByteString.Char8 qualified as BSC
 import Data.Char (toLower)
 import Data.Data
 import Data.List.NonEmpty (NonEmpty)
-import Data.Text (Text)
 import Data.Text.Encoding qualified as Text
 import GHC.Exts (IsList (..))
 import Prettyprinter
@@ -107,9 +106,6 @@ deserialiseInput
 deserialiseInput acceptedFormats inputBs =
   go (toList acceptedFormats)
  where
-  inputText :: Text
-  inputText = Text.decodeUtf8 inputBs
-
   go :: [InputFormat a] -> Either InputDecodeError a
   go [] = Left InputInvalidError
   go (kf : kfs) =
@@ -139,13 +135,19 @@ deserialiseInput acceptedFormats inputBs =
       Left _ -> DeserialiseInputErrorFormatMismatch
 
   deserialiseBech32 :: SerialiseAsBech32 a => DeserialiseInputResult a
-  deserialiseBech32 =
-    case deserialiseFromBech32 inputText of
-      Right res -> DeserialiseInputSuccess res
-      -- The input was not valid Bech32.
-      Left (Bech32DecodingError _) -> DeserialiseInputErrorFormatMismatch
-      -- The input was valid Bech32, but some other error occurred.
-      Left err -> DeserialiseInputError $ InputBech32DecodeError err
+  deserialiseBech32 = either id fromBech32 $ decodeText inputBs
+   where
+    -- The input was not valid UTF-8, so it cannot be valid Bech32.
+    decodeText =
+      first (const DeserialiseInputErrorFormatMismatch)
+        . Text.decodeUtf8'
+    fromBech32 text =
+      case deserialiseFromBech32 text of
+        Right res -> DeserialiseInputSuccess res
+        -- The input was not valid Bech32.
+        Left (Bech32DecodingError _) -> DeserialiseInputErrorFormatMismatch
+        -- The input was valid Bech32, but some other error occurred.
+        Left err -> DeserialiseInputError $ InputBech32DecodeError err
 
   deserialiseHex :: SerialiseAsRawBytes a => DeserialiseInputResult a
   deserialiseHex
@@ -179,9 +181,6 @@ deserialiseInputAnyOf bech32Types textEnvTypes inputBs =
     DeserialiseInputError err -> Left err
     DeserialiseInputErrorFormatMismatch -> Left InputInvalidError
  where
-  inputText :: Text
-  inputText = Text.decodeUtf8 inputBs
-
   orTry
     :: DeserialiseInputResult b
     -> DeserialiseInputResult b
@@ -208,13 +207,19 @@ deserialiseInputAnyOf bech32Types textEnvTypes inputBs =
       Left _ -> DeserialiseInputErrorFormatMismatch
 
   deserialiseBech32 :: DeserialiseInputResult b
-  deserialiseBech32 =
-    case deserialiseAnyOfFromBech32 bech32Types inputText of
-      Right res -> DeserialiseInputSuccess res
-      -- The input was not valid Bech32.
-      Left (Bech32DecodingError _) -> DeserialiseInputErrorFormatMismatch
-      -- The input was valid Bech32, but some other error occurred.
-      Left err -> DeserialiseInputError $ InputBech32DecodeError err
+  deserialiseBech32 = either id fromBech32 $ decodeText inputBs
+   where
+    -- The input was not valid UTF-8, so it cannot be valid Bech32.
+    decodeText =
+      first (const DeserialiseInputErrorFormatMismatch)
+        . Text.decodeUtf8'
+    fromBech32 text =
+      case deserialiseAnyOfFromBech32 bech32Types text of
+        Right res -> DeserialiseInputSuccess res
+        -- The input was not valid Bech32.
+        Left (Bech32DecodingError _) -> DeserialiseInputErrorFormatMismatch
+        -- The input was valid Bech32, but some other error occurred.
+        Left err -> DeserialiseInputError $ InputBech32DecodeError err
 
 -- | Read formatted file
 readFormattedFile
diff --git a/cardano-api/test/cardano-api-golden/Test/Golden/ErrorsSpec.hs b/cardano-api/test/cardano-api-golden/Test/Golden/ErrorsSpec.hs
index 08c26077a7..5a63ce34a4 100644
--- a/cardano-api/test/cardano-api-golden/Test/Golden/ErrorsSpec.hs
+++ b/cardano-api/test/cardano-api-golden/Test/Golden/ErrorsSpec.hs
@@ -159,6 +159,7 @@ test_Bech32DecodeError =
     , Bech32DeserialiseFromBytesError bytestring
     , Bech32WrongPrefix text text
     , Bech32UnexpectedHeader text text
+    , Bech32InvalidUtf8 text
     ]
 
 test_InputDecodeError :: TestTree
diff --git a/cardano-api/test/cardano-api-golden/files/errors/Cardano.Api.Serialise.Bech32.Bech32DecodeError/Bech32InvalidUtf8.txt b/cardano-api/test/cardano-api-golden/files/errors/Cardano.Api.Serialise.Bech32.Bech32DecodeError/Bech32InvalidUtf8.txt
new file mode 100644
index 0000000000..5338dd2070
--- /dev/null
+++ b/cardano-api/test/cardano-api-golden/files/errors/Cardano.Api.Serialise.Bech32.Bech32DecodeError/Bech32InvalidUtf8.txt
@@ -0,0 +1 @@
+The Bech32-encoded string is not valid UTF-8: <text>
\ No newline at end of file