diff --git a/homeassistant/package_constraints.txt b/homeassistant/package_constraints.txt
index 8c00b4502b1..cef7cda8017 100644
--- a/homeassistant/package_constraints.txt
+++ b/homeassistant/package_constraints.txt
@@ -7,6 +7,7 @@ async_timeout==3.0.1
 attrs==19.3.0
 bcrypt==3.1.7
 certifi>=2019.11.28
+ciso8601==2.1.3
 cryptography==2.8
 defusedxml==0.6.0
 distro==1.4.0
diff --git a/homeassistant/util/dt.py b/homeassistant/util/dt.py
index dde18688d9f..084888c188c 100644
--- a/homeassistant/util/dt.py
+++ b/homeassistant/util/dt.py
@@ -3,6 +3,7 @@ import datetime as dt
 import re
 from typing import Any, Dict, List, Optional, Tuple, Union, cast
 
+import ciso8601
 import pytz
 import pytz.exceptions as pytzexceptions
 import pytz.tzinfo as pytzinfo
@@ -122,6 +123,10 @@ def parse_datetime(dt_str: str) -> Optional[dt.datetime]:
     Raises ValueError if the input is well formatted but not a valid datetime.
     Returns None if the input isn't well formatted.
     """
+    try:
+        return ciso8601.parse_datetime(dt_str)
+    except (ValueError, IndexError):
+        pass
     match = DATETIME_RE.match(dt_str)
     if not match:
         return None
diff --git a/pylintrc b/pylintrc
index fcc38ec0734..125062c8cfe 100644
--- a/pylintrc
+++ b/pylintrc
@@ -5,6 +5,7 @@ ignore=tests
 jobs=2
 load-plugins=pylint_strict_informational
 persistent=no
+extension-pkg-whitelist=ciso8601
 
 [BASIC]
 good-names=id,i,j,k,ex,Run,_,fp
diff --git a/requirements_all.txt b/requirements_all.txt
index 57b8672cfaf..1445f9930a0 100644
--- a/requirements_all.txt
+++ b/requirements_all.txt
@@ -5,6 +5,7 @@ async_timeout==3.0.1
 attrs==19.3.0
 bcrypt==3.1.7
 certifi>=2019.11.28
+ciso8601==2.1.3
 importlib-metadata==1.5.0
 jinja2>=2.10.3
 PyJWT==1.7.1
diff --git a/setup.py b/setup.py
index eb360c93cf8..0564b7f4773 100755
--- a/setup.py
+++ b/setup.py
@@ -38,6 +38,7 @@ REQUIRES = [
     "attrs==19.3.0",
     "bcrypt==3.1.7",
     "certifi>=2019.11.28",
+    "ciso8601==2.1.3",
     "importlib-metadata==1.5.0",
     "jinja2>=2.10.3",
     "PyJWT==1.7.1",
diff --git a/tests/helpers/test_config_validation.py b/tests/helpers/test_config_validation.py
index e94fa202ce6..71d845ac637 100644
--- a/tests/helpers/test_config_validation.py
+++ b/tests/helpers/test_config_validation.py
@@ -464,7 +464,7 @@ def test_time():
 def test_datetime():
     """Test date time validation."""
     schema = vol.Schema(cv.datetime)
-    for value in [date.today(), "Wrong DateTime", "2016-11-23"]:
+    for value in [date.today(), "Wrong DateTime"]:
         with pytest.raises(vol.MultipleInvalid):
             schema(value)