diff --git a/cpp/src/parquet/metadata.cc b/cpp/src/parquet/metadata.cc
index 70c785b7359..cecfc515dd4 100644
--- a/cpp/src/parquet/metadata.cc
+++ b/cpp/src/parquet/metadata.cc
@@ -1753,7 +1753,7 @@ class ColumnChunkMetaDataBuilder::ColumnChunkMetaDataBuilderImpl {
         eck.__set_path_in_schema(column_->path()->ToDotVector());
         // check if column has its own encryption algorithm
         if (encrypt_md->parquet_cipher().has_value()) {
-          EncryptionAlgorithm column_encryption_algorithm;
+          EncryptionAlgorithm column_encryption_algorithm{};
           column_encryption_algorithm.algorithm = encrypt_md->parquet_cipher().value();
           eck.__set_encryption_algorithm(ToThrift(column_encryption_algorithm));
         }
diff --git a/cpp/src/parquet/types.h b/cpp/src/parquet/types.h
index f3b1b5d7f89..c71a06fc076 100644
--- a/cpp/src/parquet/types.h
+++ b/cpp/src/parquet/types.h
@@ -580,7 +580,7 @@ bool IsParquetCipherSupported(ParquetCipher::type cipher);
 struct AadMetadata {
   std::string aad_prefix;
   std::string aad_file_unique;
-  bool supply_aad_prefix;
+  bool supply_aad_prefix = false;
 };
 
 struct EncryptionAlgorithm {