diff --git a/extmod/modbluetooth.c b/extmod/modbluetooth.c
index caaf872e7d..8870a21c4d 100644
--- a/extmod/modbluetooth.c
+++ b/extmod/modbluetooth.c
@@ -884,6 +884,23 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bluetooth_ble_l2cap_recvinto_obj, 4,
 
 #endif // MICROPY_PY_BLUETOOTH_ENABLE_L2CAP_CHANNELS
 
+#if MICROPY_PY_BLUETOOTH_ENABLE_HCI_CMD
+
+STATIC mp_obj_t bluetooth_ble_hci_cmd(size_t n_args, const mp_obj_t *args) {
+    mp_int_t ogf = mp_obj_get_int(args[1]);
+    mp_int_t ocf = mp_obj_get_int(args[2]);
+    mp_buffer_info_t bufinfo_request = {0};
+    mp_buffer_info_t bufinfo_response = {0};
+    mp_get_buffer_raise(args[3], &bufinfo_request, MP_BUFFER_READ);
+    mp_get_buffer_raise(args[4], &bufinfo_response, MP_BUFFER_WRITE);
+    uint8_t status = 0;
+    bluetooth_handle_errno(mp_bluetooth_hci_cmd(ogf, ocf, bufinfo_request.buf, bufinfo_request.len, bufinfo_response.buf, bufinfo_response.len, &status));
+    return MP_OBJ_NEW_SMALL_INT(status);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bluetooth_ble_hci_cmd_obj, 5, 5, bluetooth_ble_hci_cmd);
+
+#endif // MICROPY_PY_BLUETOOTH_ENABLE_HCI_CMD
+
 // ----------------------------------------------------------------------------
 // Bluetooth object: Definition
 // ----------------------------------------------------------------------------
@@ -927,6 +944,9 @@ STATIC const mp_rom_map_elem_t bluetooth_ble_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_l2cap_send), MP_ROM_PTR(&bluetooth_ble_l2cap_send_obj) },
     { MP_ROM_QSTR(MP_QSTR_l2cap_recvinto), MP_ROM_PTR(&bluetooth_ble_l2cap_recvinto_obj) },
     #endif
+    #if MICROPY_PY_BLUETOOTH_ENABLE_HCI_CMD
+    { MP_ROM_QSTR(MP_QSTR_hci_cmd), MP_ROM_PTR(&bluetooth_ble_hci_cmd_obj) },
+    #endif
 };
 STATIC MP_DEFINE_CONST_DICT(bluetooth_ble_locals_dict, bluetooth_ble_locals_dict_table);
 
diff --git a/extmod/modbluetooth.h b/extmod/modbluetooth.h
index f14033de30..c96427fcb4 100644
--- a/extmod/modbluetooth.h
+++ b/extmod/modbluetooth.h
@@ -60,6 +60,12 @@
 #define MICROPY_PY_BLUETOOTH_ENABLE_PAIRING_BONDING (0)
 #endif
 
+// Optionally enable support for the `hci_cmd` function allowing
+// Python to directly low-level HCI commands.
+#ifndef MICROPY_PY_BLUETOOTH_ENABLE_HCI_CMD
+#define MICROPY_PY_BLUETOOTH_ENABLE_HCI_CMD (0)
+#endif
+
 // This is used to protect the ringbuffer.
 // A port may no-op this if MICROPY_PY_BLUETOOTH_USE_SYNC_EVENTS is enabled.
 #ifndef MICROPY_PY_BLUETOOTH_ENTER
@@ -387,6 +393,10 @@ int mp_bluetooth_l2cap_send(uint16_t conn_handle, uint16_t cid, const uint8_t *b
 int mp_bluetooth_l2cap_recvinto(uint16_t conn_handle, uint16_t cid, uint8_t *buf, size_t *len);
 #endif // MICROPY_PY_BLUETOOTH_ENABLE_L2CAP_CHANNELS
 
+#if MICROPY_PY_BLUETOOTH_ENABLE_HCI_CMD
+int mp_bluetooth_hci_cmd(uint16_t ogf, uint16_t ocf, const uint8_t *req, size_t req_len, uint8_t *resp, size_t resp_len, uint8_t *status);
+#endif // MICROPY_PY_BLUETOOTH_ENABLE_HCI_CMD
+
 /////////////////////////////////////////////////////////////////////////////
 // API implemented by modbluetooth (called by port-specific implementations):
 
diff --git a/extmod/nimble/modbluetooth_nimble.c b/extmod/nimble/modbluetooth_nimble.c
index 9ceeab7d7b..8bead890d8 100644
--- a/extmod/nimble/modbluetooth_nimble.c
+++ b/extmod/nimble/modbluetooth_nimble.c
@@ -81,9 +81,11 @@ STATIC int ble_hs_err_to_errno(int err) {
         return 0;
     }
     if (err >= 0 && (unsigned)err < MP_ARRAY_SIZE(ble_hs_err_to_errno_table) && ble_hs_err_to_errno_table[err]) {
+        // Return an MP_Exxx error code.
         return ble_hs_err_to_errno_table[err];
     } else {
-        return MP_EIO;
+        // Pass through the BLE error code.
+        return -err;
     }
 }
 
@@ -1660,6 +1662,25 @@ int mp_bluetooth_l2cap_recvinto(uint16_t conn_handle, uint16_t cid, uint8_t *buf
 
 #endif // MICROPY_PY_BLUETOOTH_ENABLE_L2CAP_CHANNELS
 
+#if MICROPY_PY_BLUETOOTH_ENABLE_HCI_CMD
+
+// For ble_hs_hci_cmd_tx
+#include "nimble/host/src/ble_hs_hci_priv.h"
+
+int mp_bluetooth_hci_cmd(uint16_t ogf, uint16_t ocf, const uint8_t *req, size_t req_len, uint8_t *resp, size_t resp_len, uint8_t *status) {
+    int rc = ble_hs_hci_cmd_tx(BLE_HCI_OP(ogf, ocf), req, req_len, resp, resp_len);
+    if (rc < BLE_HS_ERR_HCI_BASE || rc >= BLE_HS_ERR_HCI_BASE + 0x100) {
+        // The controller didn't handle the command (e.g. HCI timeout).
+        return ble_hs_err_to_errno(rc);
+    } else {
+        // The command executed, but had an error (i.e. invalid parameter).
+        *status = rc - BLE_HS_ERR_HCI_BASE;
+        return 0;
+    }
+}
+
+#endif // MICROPY_PY_BLUETOOTH_ENABLE_HCI_CMD
+
 #if MICROPY_PY_BLUETOOTH_ENABLE_PAIRING_BONDING
 
 STATIC int ble_store_ram_read(int obj_type, const union ble_store_key *key, union ble_store_value *value) {