diff --git a/changelog.d/12902.misc b/changelog.d/12902.misc
new file mode 100644
index 000000000..3ee8f9255
--- /dev/null
+++ b/changelog.d/12902.misc
@@ -0,0 +1 @@
+Remove PyNaCl occurrences directly used in Synapse code.
\ No newline at end of file
diff --git a/contrib/cmdclient/console.py b/contrib/cmdclient/console.py
index 856dd437d..895b2a7af 100755
--- a/contrib/cmdclient/console.py
+++ b/contrib/cmdclient/console.py
@@ -16,6 +16,7 @@
 
 """ Starts a synapse client console. """
 import argparse
+import binascii
 import cmd
 import getpass
 import json
@@ -26,9 +27,8 @@ import urllib
 from http import TwistedHttpClient
 from typing import Optional
 
-import nacl.encoding
-import nacl.signing
 import urlparse
+from signedjson.key import NACL_ED25519, decode_verify_key_bytes
 from signedjson.sign import SignatureVerifyException, verify_signed_json
 
 from twisted.internet import defer, reactor, threads
@@ -41,7 +41,6 @@ TRUSTED_ID_SERVERS = ["localhost:8001"]
 
 
 class SynapseCmd(cmd.Cmd):
-
     """Basic synapse command-line processor.
 
     This processes commands from the user and calls the relevant HTTP methods.
@@ -420,8 +419,8 @@ class SynapseCmd(cmd.Cmd):
                 pubKey = None
                 pubKeyObj = yield self.http_client.do_request("GET", url)
                 if "public_key" in pubKeyObj:
-                    pubKey = nacl.signing.VerifyKey(
-                        pubKeyObj["public_key"], encoder=nacl.encoding.HexEncoder
+                    pubKey = decode_verify_key_bytes(
+                        NACL_ED25519, binascii.unhexlify(pubKeyObj["public_key"])
                     )
                 else:
                     print("No public key found in pubkey response!")
diff --git a/poetry.lock b/poetry.lock
index 6b4686545..7c561e318 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -1563,7 +1563,7 @@ url_preview = ["lxml"]
 [metadata]
 lock-version = "1.1"
 python-versions = "^3.7.1"
-content-hash = "d39d5ac5d51c014581186b7691999b861058b569084c525523baf70b77f292b1"
+content-hash = "539e5326f401472d1ffc8325d53d72e544cd70156b3f43f32f1285c4c131f831"
 
 [metadata.files]
 attrs = [
diff --git a/pyproject.toml b/pyproject.toml
index 75251c863..ec6e81f25 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -113,7 +113,6 @@ unpaddedbase64 = ">=2.1.0"
 canonicaljson = ">=1.4.0"
 # we use the type definitions added in signedjson 1.1.
 signedjson = ">=1.1.0"
-PyNaCl = ">=1.2.1"
 # validating SSL certs for IP addresses requires service_identity 18.1.
 service-identity = ">=18.1.0"
 # Twisted 18.9 introduces some logger improvements that the structured
diff --git a/tests/crypto/test_event_signing.py b/tests/crypto/test_event_signing.py
index 06e0545a4..8fa710c9d 100644
--- a/tests/crypto/test_event_signing.py
+++ b/tests/crypto/test_event_signing.py
@@ -12,10 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-
-import nacl.signing
-import signedjson.types
-from unpaddedbase64 import decode_base64
+from signedjson.key import decode_signing_key_base64
+from signedjson.types import SigningKey
 
 from synapse.api.room_versions import RoomVersions
 from synapse.crypto.event_signing import add_hashes_and_signatures
@@ -25,7 +23,7 @@ from tests import unittest
 
 # Perform these tests using given secret key so we get entirely deterministic
 # signatures output that we can test against.
-SIGNING_KEY_SEED = decode_base64("YJDBA9Xnr2sVqXD9Vj7XVUnmFZcZrlw8Md7kMW+3XA1")
+SIGNING_KEY_SEED = "YJDBA9Xnr2sVqXD9Vj7XVUnmFZcZrlw8Md7kMW+3XA1"
 
 KEY_ALG = "ed25519"
 KEY_VER = "1"
@@ -36,14 +34,9 @@ HOSTNAME = "domain"
 
 class EventSigningTestCase(unittest.TestCase):
     def setUp(self):
-        # NB: `signedjson` expects `nacl.signing.SigningKey` instances which have been
-        # monkeypatched to include new `alg` and `version` attributes. This is captured
-        # by the `signedjson.types.SigningKey` protocol.
-        self.signing_key: signedjson.types.SigningKey = nacl.signing.SigningKey(  # type: ignore[assignment]
-            SIGNING_KEY_SEED
+        self.signing_key: SigningKey = decode_signing_key_base64(
+            KEY_ALG, KEY_VER, SIGNING_KEY_SEED
         )
-        self.signing_key.alg = KEY_ALG
-        self.signing_key.version = KEY_VER
 
     def test_sign_minimal(self):
         event_dict = {
diff --git a/tests/crypto/test_keyring.py b/tests/crypto/test_keyring.py
index d00ef24ca..820a1a54e 100644
--- a/tests/crypto/test_keyring.py
+++ b/tests/crypto/test_keyring.py
@@ -19,8 +19,8 @@ import attr
 import canonicaljson
 import signedjson.key
 import signedjson.sign
-from nacl.signing import SigningKey
 from signedjson.key import encode_verify_key_base64, get_verify_key
+from signedjson.types import SigningKey
 
 from twisted.internet import defer
 from twisted.internet.defer import Deferred, ensureDeferred