diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Cast.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Cast.scala
index 568927a35e87..d2e461b2cb69 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Cast.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Cast.scala
@@ -406,19 +406,21 @@ abstract class CastBase extends UnaryExpression with TimeZoneAwareExpression wit
         if (row.numFields > 0) {
           val st = fields.map(_.dataType)
           val toUTF8StringFuncs = st.map(castToString)
-          if (row.isNullAt(0)) {
+          if (fields(0).nullable && row.isNullAt(0)) {
             if (!legacyCastToStr) builder.append("null")
           } else {
-            builder.append(toUTF8StringFuncs(0)(row.get(0, st(0))).asInstanceOf[UTF8String])
+            val accessor = InternalRow.getAccessor(fields(0).dataType, fields(0).nullable)
+            builder.append(toUTF8StringFuncs(0)(accessor(row, 0)).asInstanceOf[UTF8String])
           }
           var i = 1
           while (i < row.numFields) {
             builder.append(",")
-            if (row.isNullAt(i)) {
+            if (fields(i).nullable && row.isNullAt(i)) {
               if (!legacyCastToStr) builder.append(" null")
             } else {
               builder.append(" ")
-              builder.append(toUTF8StringFuncs(i)(row.get(i, st(i))).asInstanceOf[UTF8String])
+              val accessor = InternalRow.getAccessor(fields(i).dataType, fields(i).nullable)
+              builder.append(toUTF8StringFuncs(i)(accessor(row, i)).asInstanceOf[UTF8String])
             }
             i += 1
           }
@@ -868,8 +870,13 @@ abstract class CastBase extends UnaryExpression with TimeZoneAwareExpression wit
       val newRow = new GenericInternalRow(from.fields.length)
       var i = 0
       while (i < row.numFields) {
-        newRow.update(i,
-          if (row.isNullAt(i)) null else castFuncs(i)(row.get(i, from.apply(i).dataType)))
+        val value = if (from.fields(i).nullable && row.isNullAt(i)) {
+          null
+        } else {
+          val accessor = InternalRow.getAccessor(from.fields(i).dataType, from.fields(i).nullable)
+          castFuncs(i)(accessor(row, i))
+        }
+        newRow.update(i, value)
         i += 1
       }
       newRow
@@ -1098,29 +1105,37 @@ abstract class CastBase extends UnaryExpression with TimeZoneAwareExpression wit
   }
 
   private def writeStructToStringBuilder(
-      st: Seq[DataType],
+      st: Seq[StructField],
       row: ExprValue,
       buffer: ExprValue,
       ctx: CodegenContext): Block = {
-    val structToStringCode = st.zipWithIndex.map { case (ft, i) =>
-      val fieldToStringCode = castToStringCode(ft, ctx)
-      val field = ctx.freshVariable("field", ft)
-      val fieldStr = ctx.freshVariable("fieldStr", StringType)
-      val javaType = JavaCode.javaType(ft)
-      code"""
-         |${if (i != 0) code"""$buffer.append(",");""" else EmptyBlock}
-         |if ($row.isNullAt($i)) {
-         |  ${appendIfNotLegacyCastToStr(buffer, if (i == 0) "null" else " null")}
-         |} else {
-         |  ${if (i != 0) code"""$buffer.append(" ");""" else EmptyBlock}
-         |
-         |  // Append $i field into the string buffer
-         |  $javaType $field = ${CodeGenerator.getValue(row, ft, s"$i")};
-         |  UTF8String $fieldStr = null;
-         |  ${fieldToStringCode(field, fieldStr, null /* resultIsNull won't be used */)}
-         |  $buffer.append($fieldStr);
-         |}
-       """.stripMargin
+    val structToStringCode = st.zipWithIndex.map {
+      case (StructField(_, dataType, nullable, _), i) =>
+        val fieldToStringCode = castToStringCode(dataType, ctx)
+        val field = ctx.freshVariable("field", dataType)
+        val fieldStr = ctx.freshVariable("fieldStr", StringType)
+        val javaType = JavaCode.javaType(dataType)
+
+        val isNull = if (nullable) {
+          code"$row.isNullAt($i)"
+        } else {
+          code"false"
+        }
+
+        code"""
+           |${if (i != 0) code"""$buffer.append(",");""" else EmptyBlock}
+           |if ($isNull) {
+           |  ${appendIfNotLegacyCastToStr(buffer, if (i == 0) "null" else " null")}
+           |} else {
+           |  ${if (i != 0) code"""$buffer.append(" ");""" else EmptyBlock}
+           |
+           |  // Append $i field into the string buffer
+           |  $javaType $field = ${CodeGenerator.getValue(row, dataType, s"$i")};
+           |  UTF8String $fieldStr = null;
+           |  ${fieldToStringCode(field, fieldStr, null /* resultIsNull won't be used */)}
+           |  $buffer.append($fieldStr);
+           |}
+         """.stripMargin
     }
 
     val writeStructCode = ctx.splitExpressions(
@@ -1184,7 +1199,7 @@ abstract class CastBase extends UnaryExpression with TimeZoneAwareExpression wit
           val row = ctx.freshVariable("row", classOf[InternalRow])
           val buffer = ctx.freshVariable("buffer", classOf[UTF8StringBuilder])
           val bufferClass = JavaCode.javaType(classOf[UTF8StringBuilder])
-          val writeStructCode = writeStructToStringBuilder(fields.map(_.dataType), row, buffer, ctx)
+          val writeStructCode = writeStructToStringBuilder(fields, row, buffer, ctx)
           code"""
              |InternalRow $row = $c;
              |$bufferClass $buffer = new $bufferClass();
@@ -1890,8 +1905,15 @@ abstract class CastBase extends UnaryExpression with TimeZoneAwareExpression wit
       val toFieldNull = ctx.freshVariable("tfn", BooleanType)
       val fromType = JavaCode.javaType(from.fields(i).dataType)
       val setColumn = CodeGenerator.setColumn(tmpResult, to.fields(i).dataType, i, toFieldPrim)
+
+      val isNull = if (from.fields(i).nullable) {
+        code"boolean $fromFieldNull = $tmpInput.isNullAt($i);"
+      } else {
+        code"boolean $fromFieldNull = false;"
+      }
+
       code"""
-        boolean $fromFieldNull = $tmpInput.isNullAt($i);
+        $isNull
         if ($fromFieldNull) {
           $tmpResult.setNullAt($i);
         } else {
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CastSuiteBase.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CastSuiteBase.scala
index 48835bf9db2c..f10a82c6ca44 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CastSuiteBase.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CastSuiteBase.scala
@@ -1271,4 +1271,49 @@ abstract class CastSuiteBase extends SparkFunSuite with ExpressionEvalHelper {
         }
     }
   }
+
+  test("SPARK-35912: Cast struct contains the null value to string") {
+    Seq(true, false).foreach { nullable =>
+        val lit = Literal.create(InternalRow(InternalRow(1, null)),
+          StructType(Seq(StructField("c1",
+            StructType(Seq(
+              StructField("c2", IntegerType, true),
+              StructField("c3", IntegerType, nullable)
+            ))
+          )))
+        )
+        val ret = cast(lit, StringType)
+        assert(ret.resolved)
+        val expected = if (nullable) {
+          "{{1, null}}"
+        } else {
+          "{{1, 0}}"
+        }
+        checkEvaluation(ret, expected)
+    }
+  }
+
+  test("SPARK-35912: Cast struct contains the null value to struct") {
+    Seq(true, false).foreach { nullable =>
+      val lit = Literal.create(InternalRow(1, null),
+        StructType(Seq(
+          StructField("c1", IntegerType, true),
+          StructField("c2", IntegerType, nullable)
+        ))
+      )
+      val toType = StructType(Seq(
+        StructField("c1", StringType, true),
+        StructField("c2", StringType, true)
+      ))
+
+      val expected = if (nullable) {
+        InternalRow(UTF8String.fromString("1"), null)
+      } else {
+        InternalRow(UTF8String.fromString("1"), UTF8String.fromString("0"))
+      }
+      val ret = cast(lit, toType)
+      assert(ret.resolved)
+      checkEvaluation(ret, expected)
+    }
+  }
 }