diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/data_class_opt_var.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/data_class_opt_var.mustache
index deae3ebd5dc..2ce65fd1d16 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/data_class_opt_var.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/data_class_opt_var.mustache
@@ -18,4 +18,4 @@
     {{#deprecated}}
     @Deprecated(message = "This property is deprecated.")
     {{/deprecated}}
-    {{#multiplatform}}@SerialName(value = "{{{vendorExtensions.x-base-name-literal}}}") {{/multiplatform}}{{#isInherited}}override {{/isInherited}}{{>modelMutable}} {{{name}}}: {{#isArray}}{{#isList}}kotlin.collections.List{{/isList}}{{^isList}}kotlin.Array{{/isList}}<{{^items.isEnum}}{{^items.isPrimitiveType}}{{^items.isModel}}{{#kotlinx_serialization}}@Contextual {{/kotlinx_serialization}}{{/items.isModel}}{{/items.isPrimitiveType}}{{{items.dataType}}}{{/items.isEnum}}{{#items.isEnum}}{{classname}}.{{{nameInCamelCase}}}{{/items.isEnum}}>{{/isArray}}{{^isEnum}}{{^isArray}}{{{dataType}}}{{/isArray}}{{/isEnum}}{{#isEnum}}{{^isArray}}{{classname}}.{{{nameInCamelCase}}}{{/isArray}}{{/isEnum}}? = {{#defaultvalue}}{{defaultvalue}}{{/defaultvalue}}{{^defaultvalue}}null{{/defaultvalue}}
\ No newline at end of file
+    {{#multiplatform}}@SerialName(value = "{{{vendorExtensions.x-base-name-literal}}}") {{/multiplatform}}{{#isInherited}}override {{/isInherited}}{{>modelMutable}} {{{name}}}: {{#isArray}}{{#isList}}{{#uniqueItems}}kotlin.collections.Set{{/uniqueItems}}{{^uniqueItems}}kotlin.collections.List{{/uniqueItems}}{{/isList}}{{^isList}}kotlin.Array{{/isList}}<{{^items.isEnum}}{{^items.isPrimitiveType}}{{^items.isModel}}{{#kotlinx_serialization}}@Contextual {{/kotlinx_serialization}}{{/items.isModel}}{{/items.isPrimitiveType}}{{{items.dataType}}}{{/items.isEnum}}{{#items.isEnum}}{{classname}}.{{{nameInCamelCase}}}{{/items.isEnum}}>{{/isArray}}{{^isEnum}}{{^isArray}}{{{dataType}}}{{/isArray}}{{/isEnum}}{{#isEnum}}{{^isArray}}{{classname}}.{{{nameInCamelCase}}}{{/isArray}}{{/isEnum}}? = {{#defaultvalue}}{{defaultvalue}}{{/defaultvalue}}{{^defaultvalue}}null{{/defaultvalue}}
\ No newline at end of file
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/data_class_req_var.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/data_class_req_var.mustache
index 2c44be195c8..d7a2fcf31bd 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/data_class_req_var.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/data_class_req_var.mustache
@@ -18,4 +18,4 @@
     {{#deprecated}}
     @Deprecated(message = "This property is deprecated.")
     {{/deprecated}}
-    {{#multiplatform}}@SerialName(value = "{{{vendorExtensions.x-base-name-literal}}}") @Required {{/multiplatform}}{{#isInherited}}override {{/isInherited}}{{>modelMutable}} {{{name}}}: {{#isArray}}{{#isList}}kotlin.collections.List{{/isList}}{{^isList}}kotlin.Array{{/isList}}<{{^items.isEnum}}{{^items.isPrimitiveType}}{{^items.isModel}}{{#kotlinx_serialization}}@Contextual {{/kotlinx_serialization}}{{/items.isModel}}{{/items.isPrimitiveType}}{{{items.dataType}}}{{/items.isEnum}}{{#items.isEnum}}{{classname}}.{{{nameInCamelCase}}}{{/items.isEnum}}>{{/isArray}}{{^isEnum}}{{^isArray}}{{{dataType}}}{{/isArray}}{{/isEnum}}{{#isEnum}}{{^isArray}}{{classname}}.{{{nameInCamelCase}}}{{/isArray}}{{/isEnum}}{{#isNullable}}?{{/isNullable}}
\ No newline at end of file
+    {{#multiplatform}}@SerialName(value = "{{{vendorExtensions.x-base-name-literal}}}") @Required {{/multiplatform}}{{#isInherited}}override {{/isInherited}}{{>modelMutable}} {{{name}}}: {{#isArray}}{{#isList}}{{#isUniqueItems}}kotlin.collections.Set{{/isUniqueItems}}{{^isUniqueItems}}kotlin.collections.List{{/isUniqueItems}}{{/isList}}{{^isList}}kotlin.Array{{/isList}}<{{^items.isEnum}}{{^items.isPrimitiveType}}{{^items.isModel}}{{#kotlinx_serialization}}@Contextual {{/kotlinx_serialization}}{{/items.isModel}}{{/items.isPrimitiveType}}{{{items.dataType}}}{{/items.isEnum}}{{#items.isEnum}}{{classname}}.{{{nameInCamelCase}}}{{/items.isEnum}}>{{/isArray}}{{^isEnum}}{{^isArray}}{{{dataType}}}{{/isArray}}{{/isEnum}}{{#isEnum}}{{^isArray}}{{classname}}.{{{nameInCamelCase}}}{{/isArray}}{{/isEnum}}{{#isNullable}}?{{/isNullable}}
\ No newline at end of file
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/kotlin/KotlinModelCodegenTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/kotlin/KotlinModelCodegenTest.java
index 19829496e23..af675c8913d 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/kotlin/KotlinModelCodegenTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/kotlin/KotlinModelCodegenTest.java
@@ -52,12 +52,17 @@ public class KotlinModelCodegenTest {
     }
 
     private void checkModel(AbstractKotlinCodegen codegen, boolean mutable, String... props) throws IOException {
+        String outputPath = generateModels(codegen, "src/test/resources/3_0/generic.yaml", mutable);
+        assertFileContains(Paths.get(outputPath + "/src/main/kotlin/models/Animal.kt"), props);
+    }
+
+    private String generateModels(AbstractKotlinCodegen codegen, String fileName, boolean mutable) throws IOException {
         File output = Files.createTempDirectory("test").toFile().getCanonicalFile();
         output.deleteOnExit();
         String outputPath = output.getAbsolutePath().replace('\\', '/');
 
         OpenAPI openAPI = new OpenAPIParser()
-                .readLocation("src/test/resources/3_0/generic.yaml", null, new ParseOptions()).getOpenAPI();
+                .readLocation(fileName, null, new ParseOptions()).getOpenAPI();
         codegen.setOutputDir(output.getAbsolutePath());
 
         codegen.additionalProperties().put(CodegenConstants.MODEL_PACKAGE, "models");
@@ -77,6 +82,34 @@ public class KotlinModelCodegenTest {
 
         generator.opts(input).generate();
 
-        assertFileContains(Paths.get(outputPath + "/src/main/kotlin/models/Animal.kt"), props);
+        return outputPath;
+    }
+
+    @Test(dataProvider = "generators")
+    public void valuesArrayWithUniqueItems(AbstractKotlinCodegen codegen) throws IOException {
+        String outputPath = generateModels(codegen, "src/test/resources/3_0/issue_9848.yaml", false);
+
+        assertFileContains(Paths.get(outputPath + "/src/main/kotlin/models/NonUniqueArray.kt"),
+                codegen instanceof KotlinVertxServerCodegen || codegen instanceof KotlinServerDeprecatedCodegen
+                        ? "val array: kotlin.Array<kotlin.String>"
+                        : "val array: kotlin.collections.List<kotlin.String>"
+        );
+
+        assertFileContains(Paths.get(outputPath + "/src/main/kotlin/models/UniqueArray.kt"),
+                "val array: kotlin.collections.Set<kotlin.String>");
+    }
+
+    @Test(dataProvider = "generators")
+    public void mutableArrayWithUniqueItems(AbstractKotlinCodegen codegen) throws IOException {
+        String outputPath = generateModels(codegen, "src/test/resources/3_0/issue_9848.yaml", true);
+
+        assertFileContains(Paths.get(outputPath + "/src/main/kotlin/models/NonUniqueArray.kt"),
+                codegen instanceof KotlinVertxServerCodegen || codegen instanceof KotlinServerDeprecatedCodegen
+                        ? "var array: kotlin.Array<kotlin.String>"
+                        : "var array: kotlin.collections.List<kotlin.String>"
+        );
+
+        assertFileContains(Paths.get(outputPath + "/src/main/kotlin/models/UniqueArray.kt"),
+                "var array: kotlin.collections.Set<kotlin.String>");
     }
 }
diff --git a/modules/openapi-generator/src/test/resources/3_0/issue_9848.yaml b/modules/openapi-generator/src/test/resources/3_0/issue_9848.yaml
new file mode 100644
index 00000000000..5fc12434df5
--- /dev/null
+++ b/modules/openapi-generator/src/test/resources/3_0/issue_9848.yaml
@@ -0,0 +1,50 @@
+openapi: 3.0.1
+info:
+  title: OpenAPI Petstore
+  description: "sample spec"
+  license:
+    name: Apache-2.0
+    url: https://www.apache.org/licenses/LICENSE-2.0.html
+  version: 1.0.0
+servers:
+  - url: http://petstore.swagger.io:80/v2
+tags:
+  - name: isX
+    description: an api that ensures that isX properties are present on Schema classes
+paths:
+  /uniqueTypes:
+    get:
+      responses:
+        '200':
+          description: 'unique array'
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/uniqueArray'
+  /nonUniqueTypes:
+    get:
+      responses:
+        '200':
+          description: 'non-unique array'
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/nonUniqueArray'
+components:
+  schemas:
+    uniqueArray:
+      type: object
+      properties:
+        array:
+          type: array
+          items:
+            type: string
+          uniqueItems: true
+    nonUniqueArray:
+      type: object
+      properties:
+        array:
+          type: array
+          items:
+            type: string
+          uniqueItems: false