diff --git a/src/init.cpp b/src/init.cpp
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1030,6 +1030,10 @@
     argsman.AddArg("-uacomment=<cmt>",
                    "Append comment to the user agent string",
                    ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
+    argsman.AddArg(
+        "-useragent=<ua>",
+        "Override user agent name to a specific string (overrides -uacomment)",
+        ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
 
     SetupChainParamsBaseOptions(argsman);
 
@@ -2283,6 +2287,19 @@
                                        chainman, *node.mempool));
     RegisterValidationInterface(node.peerman.get());
 
+    if (args.IsArgSet("-useragent")) {
+        const std::string ua = args.GetArg("-useragent", "");
+        if (ua != SanitizeString(ua, SAFE_CHARS_DEFAULT)) {
+            return InitError(strprintf(
+                _("User Agent (%s) contains invalid characters."), ua));
+        }
+        if (ua.size() > MAX_SUBVERSION_LENGTH) {
+            return InitError(strprintf(
+                _("Length of explicitly set User Agent (%i) exceeds maximum "
+                  "length (%i). Reduce the size of -useragent."),
+                ua.size(), MAX_SUBVERSION_LENGTH));
+        }
+    }
     // sanitize comments per BIP-0014, format user agent and check total size
     std::vector<std::string> uacomments;
     for (const std::string &cmt : args.GetArgs("-uacomment")) {
diff --git a/src/net.cpp b/src/net.cpp
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -3143,6 +3143,9 @@
 }
 
 std::string userAgent(const Config &config) {
+    if (gArgs.IsArgSet("-useragent")) {
+        return gArgs.GetArg("-useragent", "");
+    }
     // format excessive blocksize value
     std::string eb = getSubVersionEB(config.GetMaxBlockSize());
     std::vector<std::string> uacomments;
diff --git a/test/functional/feature_useragent.py b/test/functional/feature_useragent.py
new file mode 100755
--- /dev/null
+++ b/test/functional/feature_useragent.py
@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+# Copyright (c) 2021 The Bitcoin developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Test the -uaclient option."""
+
+import re
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.test_node import ErrorMatch
+from test_framework.util import assert_equal
+
+
+class UseragentTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.num_nodes = 1
+        self.setup_clean_chain = True
+
+    def run_test(self):
+        self.log.info("test -useragent")
+        default_useragent = self.nodes[0].getnetworkinfo()["subversion"]
+        expected = "/Bitcoin ABC:"
+        assert_equal(default_useragent[:len(expected)], expected)
+
+        self.restart_node(0, ["-useragent=/Foo:2000/"])
+        foo_ua = self.nodes[0].getnetworkinfo()["subversion"]
+        assert_equal(foo_ua, "/Foo:2000/")
+
+        self.log.info("test -useragent overrides -uacomment")
+        self.restart_node(0, ["-useragent=/Bar:3000/", "-uacomment=eggs"])
+        bar_ua = self.nodes[0].getnetworkinfo()["subversion"]
+        assert_equal(bar_ua, "/Bar:3000/")
+
+        self.log.info("test -useragent max length")
+        self.stop_node(0)
+        expected = r"Error: Length of explicitly set User Agent \([0-9]+\) exceeds maximum length \([0-9]+\)\. Reduce the size of -useragent\."
+        self.nodes[0].assert_start_raises_init_error(
+            ["-useragent=" + 'a' * 257], expected, match=ErrorMatch.FULL_REGEX)
+
+        self.log.info("test -uacomment invalid characters")
+        for invalid_char in ['*', '!', '₿', '🏃']:
+            expected = r"Error: User Agent \(" + \
+                re.escape(invalid_char) + r"\) contains invalid characters\."
+            self.nodes[0].assert_start_raises_init_error(
+                ["-useragent=" + invalid_char], expected, match=ErrorMatch.FULL_REGEX)
+
+
+if __name__ == '__main__':
+    UseragentTest().main()