diff --git a/datafusion/expr/src/expr_schema.rs b/datafusion/expr/src/expr_schema.rs
index 2433024e38a..bbb414655c2 100644
--- a/datafusion/expr/src/expr_schema.rs
+++ b/datafusion/expr/src/expr_schema.rs
@@ -170,7 +170,9 @@ impl ExprSchemable for Expr {
                 } else if let Some(e) = else_expr {
                     e.nullable(input_schema)
                 } else {
-                    Ok(false)
+                    // CASE produces NULL if there is no `else` expr
+                    // (aka when none of the `when_then_exprs` match)
+                    Ok(true)
                 }
             }
             Expr::Cast { expr, .. } => expr.nullable(input_schema),
diff --git a/datafusion/physical-expr/src/expressions/case.rs b/datafusion/physical-expr/src/expressions/case.rs
index aa6d05ab974..4c62c1d575f 100644
--- a/datafusion/physical-expr/src/expressions/case.rs
+++ b/datafusion/physical-expr/src/expressions/case.rs
@@ -269,7 +269,9 @@ impl PhysicalExpr for CaseExpr {
         } else if let Some(e) = &self.else_expr {
             e.nullable(input_schema)
         } else {
-            Ok(false)
+            // CASE produces NULL if there is no `else` expr
+            // (aka when none of the `when_then_exprs` match)
+            Ok(true)
         }
     }