diff --git a/doc/source/whatsnew/v1.2.0.rst b/doc/source/whatsnew/v1.2.0.rst
index a963442ecda1c..66ab954bae288 100644
--- a/doc/source/whatsnew/v1.2.0.rst
+++ b/doc/source/whatsnew/v1.2.0.rst
@@ -492,6 +492,7 @@ Other
 - Fixed metadata propagation in the :class:`Series.dt` and :class:`Series.str` accessors (:issue:`28283`)
 - Bug in :meth:`Index.union` behaving differently depending on whether operand is a :class:`Index` or other list-like (:issue:`36384`)
 - Passing an array with 2 or more dimensions to the :class:`Series` constructor now raises the more specific ``ValueError``, from a bare ``Exception`` previously (:issue:`35744`)
+- Bug in ``accessor.DirNamesMixin``, where ``dir(obj)`` wouldn't show attributes defined on the instance (:issue:`37173`).
 
 .. ---------------------------------------------------------------------------
 
diff --git a/pandas/core/accessor.py b/pandas/core/accessor.py
index 2caf1f75f3da1..41212fd49113d 100644
--- a/pandas/core/accessor.py
+++ b/pandas/core/accessor.py
@@ -4,7 +4,7 @@
 that can be mixed into or pinned onto other pandas classes.
 
 """
-from typing import FrozenSet, Set
+from typing import FrozenSet, List, Set
 import warnings
 
 from pandas.util._decorators import doc
@@ -12,15 +12,15 @@
 
 class DirNamesMixin:
     _accessors: Set[str] = set()
-    _deprecations: FrozenSet[str] = frozenset()
+    _hidden_attrs: FrozenSet[str] = frozenset()
 
-    def _dir_deletions(self):
+    def _dir_deletions(self) -> Set[str]:
         """
         Delete unwanted __dir__ for this object.
         """
-        return self._accessors | self._deprecations
+        return self._accessors | self._hidden_attrs
 
-    def _dir_additions(self):
+    def _dir_additions(self) -> Set[str]:
         """
         Add additional __dir__ for this object.
         """
@@ -33,7 +33,7 @@ def _dir_additions(self):
                 pass
         return rv
 
-    def __dir__(self):
+    def __dir__(self) -> List[str]:
         """
         Provide method name lookup and completion.
 
@@ -41,7 +41,7 @@ def __dir__(self):
         -----
         Only provide 'public' methods.
         """
-        rv = set(dir(type(self)))
+        rv = set(super().__dir__())
         rv = (rv - self._dir_deletions()) | self._dir_additions()
         return sorted(rv)
 
diff --git a/pandas/core/arrays/categorical.py b/pandas/core/arrays/categorical.py
index 081a363ce03c6..62dd3f89770cd 100644
--- a/pandas/core/arrays/categorical.py
+++ b/pandas/core/arrays/categorical.py
@@ -288,7 +288,7 @@ class Categorical(NDArrayBackedExtensionArray, PandasObject, ObjectStringArrayMi
     __array_priority__ = 1000
     _dtype = CategoricalDtype(ordered=False)
     # tolist is not actually deprecated, just suppressed in the __dir__
-    _deprecations = PandasObject._deprecations | frozenset(["tolist"])
+    _hidden_attrs = PandasObject._hidden_attrs | frozenset(["tolist"])
     _typ = "categorical"
     _can_hold_na = True
 
diff --git a/pandas/core/arrays/sparse/array.py b/pandas/core/arrays/sparse/array.py
index 2e62fade93dcb..4346e02069667 100644
--- a/pandas/core/arrays/sparse/array.py
+++ b/pandas/core/arrays/sparse/array.py
@@ -270,7 +270,7 @@ class SparseArray(OpsMixin, PandasObject, ExtensionArray):
     """
 
     _subtyp = "sparse_array"  # register ABCSparseArray
-    _deprecations = PandasObject._deprecations | frozenset(["get_values"])
+    _hidden_attrs = PandasObject._hidden_attrs | frozenset(["get_values"])
     _sparse_index: SparseIndex
 
     def __init__(
diff --git a/pandas/core/base.py b/pandas/core/base.py
index 6af537dcd149a..55cb671278050 100644
--- a/pandas/core/base.py
+++ b/pandas/core/base.py
@@ -314,7 +314,7 @@ class IndexOpsMixin(OpsMixin):
 
     # ndarray compatibility
     __array_priority__ = 1000
-    _deprecations: FrozenSet[str] = frozenset(
+    _hidden_attrs: FrozenSet[str] = frozenset(
         ["tolist"]  # tolist is not deprecated, just suppressed in the __dir__
     )
 
diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index 539275c7ff617..2efad0210778c 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -420,7 +420,7 @@ def _constructor(self) -> Type[DataFrame]:
         return DataFrame
 
     _constructor_sliced: Type[Series] = Series
-    _deprecations: FrozenSet[str] = NDFrame._deprecations | frozenset([])
+    _hidden_attrs: FrozenSet[str] = NDFrame._hidden_attrs | frozenset([])
     _accessors: Set[str] = {"sparse"}
 
     @property
diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index a8586e3b90083..8b2d4ee485202 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -197,7 +197,7 @@ class NDFrame(PandasObject, SelectionMixin, indexing.IndexingMixin):
     ]
     _internal_names_set: Set[str] = set(_internal_names)
     _accessors: Set[str] = set()
-    _deprecations: FrozenSet[str] = frozenset(["get_values", "tshift"])
+    _hidden_attrs: FrozenSet[str] = frozenset(["get_values", "tshift"])
     _metadata: List[str] = []
     _is_copy = None
     _mgr: BlockManager
diff --git a/pandas/core/groupby/groupby.py b/pandas/core/groupby/groupby.py
index 4ab40e25db84e..b26b48910f59b 100644
--- a/pandas/core/groupby/groupby.py
+++ b/pandas/core/groupby/groupby.py
@@ -489,6 +489,21 @@ def group_selection_context(groupby: "BaseGroupBy") -> Iterator["BaseGroupBy"]:
 class BaseGroupBy(PandasObject, SelectionMixin, Generic[FrameOrSeries]):
     _group_selection: Optional[IndexLabel] = None
     _apply_allowlist: FrozenSet[str] = frozenset()
+    _hidden_attrs = PandasObject._hidden_attrs | {
+        "as_index",
+        "axis",
+        "dropna",
+        "exclusions",
+        "grouper",
+        "group_keys",
+        "keys",
+        "level",
+        "mutated",
+        "obj",
+        "observed",
+        "sort",
+        "squeeze",
+    }
 
     def __init__(
         self,
diff --git a/pandas/core/indexes/accessors.py b/pandas/core/indexes/accessors.py
index b9b2c4b07d37a..1dd85d072f253 100644
--- a/pandas/core/indexes/accessors.py
+++ b/pandas/core/indexes/accessors.py
@@ -28,6 +28,11 @@
 
 
 class Properties(PandasDelegate, PandasObject, NoNewAttributesMixin):
+    _hidden_attrs = PandasObject._hidden_attrs | {
+        "orig",
+        "name",
+    }
+
     def __init__(self, data: "Series", orig):
         if not isinstance(data, ABCSeries):
             raise TypeError(
diff --git a/pandas/core/indexes/base.py b/pandas/core/indexes/base.py
index 6b71e455782e3..4bcc237c996ad 100644
--- a/pandas/core/indexes/base.py
+++ b/pandas/core/indexes/base.py
@@ -193,9 +193,9 @@ class Index(IndexOpsMixin, PandasObject):
     """
 
     # tolist is not actually deprecated, just suppressed in the __dir__
-    _deprecations: FrozenSet[str] = (
-        PandasObject._deprecations
-        | IndexOpsMixin._deprecations
+    _hidden_attrs: FrozenSet[str] = (
+        PandasObject._hidden_attrs
+        | IndexOpsMixin._hidden_attrs
         | frozenset(["contains", "set_value"])
     )
 
diff --git a/pandas/core/indexes/multi.py b/pandas/core/indexes/multi.py
index d012d5704f716..f7d8bb3601ec5 100644
--- a/pandas/core/indexes/multi.py
+++ b/pandas/core/indexes/multi.py
@@ -258,7 +258,7 @@ class MultiIndex(Index):
     of the mentioned helper methods.
     """
 
-    _deprecations = Index._deprecations | frozenset()
+    _hidden_attrs = Index._hidden_attrs | frozenset()
 
     # initialize to zero-length tuples to make everything work
     _typ = "multiindex"
diff --git a/pandas/core/series.py b/pandas/core/series.py
index 55aa32dd028ef..c9b307d6c4380 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -181,9 +181,9 @@ class Series(base.IndexOpsMixin, generic.NDFrame):
     _metadata: List[str] = ["name"]
     _internal_names_set = {"index"} | generic.NDFrame._internal_names_set
     _accessors = {"dt", "cat", "str", "sparse"}
-    _deprecations = (
-        base.IndexOpsMixin._deprecations
-        | generic.NDFrame._deprecations
+    _hidden_attrs = (
+        base.IndexOpsMixin._hidden_attrs
+        | generic.NDFrame._hidden_attrs
         | frozenset(["compress", "ptp"])
     )
 
diff --git a/pandas/tests/test_register_accessor.py b/pandas/tests/test_register_accessor.py
index d839936f731a3..6e224245076ee 100644
--- a/pandas/tests/test_register_accessor.py
+++ b/pandas/tests/test_register_accessor.py
@@ -4,6 +4,22 @@
 
 import pandas as pd
 import pandas._testing as tm
+from pandas.core import accessor
+
+
+def test_dirname_mixin():
+    # GH37173
+
+    class X(accessor.DirNamesMixin):
+        x = 1
+        y: int
+
+        def __init__(self):
+            self.z = 3
+
+    result = [attr_name for attr_name in dir(X()) if not attr_name.startswith("_")]
+
+    assert result == ["x", "z"]
 
 
 @contextlib.contextmanager