diff --git a/crates/nu-engine/src/eval.rs b/crates/nu-engine/src/eval.rs
index 86acdc628d..16572d8ad8 100644
--- a/crates/nu-engine/src/eval.rs
+++ b/crates/nu-engine/src/eval.rs
@@ -191,6 +191,7 @@ pub fn eval_expression(
                 Operator::Equal => lhs.eq(op_span, &rhs),
                 Operator::NotEqual => lhs.ne(op_span, &rhs),
                 Operator::In => lhs.r#in(op_span, &rhs),
+                Operator::NotIn => lhs.not_in(op_span, &rhs),
                 x => Err(ShellError::UnsupportedOperator(x, op_span)),
             }
         }
diff --git a/crates/nu-parser/src/type_check.rs b/crates/nu-parser/src/type_check.rs
index d2f972cabf..ca087d0a87 100644
--- a/crates/nu-parser/src/type_check.rs
+++ b/crates/nu-parser/src/type_check.rs
@@ -295,6 +295,28 @@ pub fn math_result_type(
                     )
                 }
             },
+            Operator::NotIn => match (&lhs.ty, &rhs.ty) {
+                (t, Type::List(u)) if type_compatible(t, u) => (Type::Bool, None),
+                (Type::Int | Type::Float, Type::Range) => (Type::Bool, None),
+                (Type::String, Type::String) => (Type::Bool, None),
+                (Type::String, Type::Record(_, _)) => (Type::Bool, None),
+
+                (Type::Unknown, _) => (Type::Bool, None),
+                (_, Type::Unknown) => (Type::Bool, None),
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Unknown,
+                        Some(ParseError::UnsupportedOperation(
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                            rhs.span,
+                            rhs.ty.clone(),
+                        )),
+                    )
+                }
+            },
 
             _ => {
                 *op = Expression::garbage(op.span);
diff --git a/crates/nu-protocol/src/value/mod.rs b/crates/nu-protocol/src/value/mod.rs
index 0ad12a9864..4b8e6b7948 100644
--- a/crates/nu-protocol/src/value/mod.rs
+++ b/crates/nu-protocol/src/value/mod.rs
@@ -812,7 +812,7 @@ impl Value {
 
         match self.partial_cmp(rhs) {
             Some(ordering) => Ok(Value::Bool {
-                val: !matches!(ordering, Ordering::Less),
+                val: !matches!(ordering, Ordering::Equal),
                 span,
             }),
             None => Err(ShellError::OperatorMismatch {
@@ -846,7 +846,7 @@ impl Value {
                 span,
             }),
             (lhs, Value::Stream { stream: rhs, .. }) => Ok(Value::Bool {
-                // TODO(@arthur-targaryen): Not sure about this clone.
+                // TODO(@arthur-targaryen): Not sure about this clone (see also `Value::not_in`).
                 val: rhs.clone().any(|x| lhs == &x),
                 span,
             }),
@@ -859,6 +859,41 @@ impl Value {
             }),
         }
     }
+
+    pub fn not_in(&self, op: Span, rhs: &Value) -> Result<Value, ShellError> {
+        let span = span(&[self.span(), rhs.span()]);
+
+        match (self, rhs) {
+            (lhs, Value::Range { val: rhs, .. }) => Ok(Value::Bool {
+                val: !rhs.contains(lhs),
+                span,
+            }),
+            (Value::String { val: lhs, .. }, Value::String { val: rhs, .. }) => Ok(Value::Bool {
+                val: !rhs.contains(lhs),
+                span,
+            }),
+            (lhs, Value::List { vals: rhs, .. }) => Ok(Value::Bool {
+                val: !rhs.contains(lhs),
+                span,
+            }),
+            (Value::String { val: lhs, .. }, Value::Record { cols: rhs, .. }) => Ok(Value::Bool {
+                val: !rhs.contains(lhs),
+                span,
+            }),
+            (lhs, Value::Stream { stream: rhs, .. }) => Ok(Value::Bool {
+                // TODO(@arthur-targaryen): Not sure about this clone (see also `Value::r#in`).
+                val: rhs.clone().all(|x| lhs != &x),
+                span,
+            }),
+            _ => Err(ShellError::OperatorMismatch {
+                op_span: op,
+                lhs_ty: self.get_type(),
+                lhs_span: self.span(),
+                rhs_ty: rhs.get_type(),
+                rhs_span: rhs.span(),
+            }),
+        }
+    }
 }
 
 /// Format a duration in nanoseconds into a string
diff --git a/src/tests.rs b/src/tests.rs
index 2de6466fbe..7d9ca9707e 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -631,3 +631,13 @@ fn string_in_valuestream() -> TestResult {
         "true",
     )
 }
+
+#[test]
+fn string_not_in_string() -> TestResult {
+    run_test(r#"'d' not-in 'abc'"#, "true")
+}
+
+#[test]
+fn float_not_in_inc_range() -> TestResult {
+    run_test(r#"1.4 not-in 2..9.42"#, "true")
+}