diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -2770,10 +2770,48 @@
     return result;
 }
 
+static UniValue findforkhash(const Config &config,
+                             const JSONRPCRequest &request) {
+    if (request.fHelp || request.params.size() != 1) {
+        throw std::runtime_error(RPCHelpMan{
+            "findforkhash",
+            "Finds the last common block hash between the parameter chain and "
+            "a locator block defined by a given block hash",
+            {
+                {"blockhash", RPCArg::Type::STR_HEX, /* opt */ false,
+                 /* default_val */ "", "The block hash of the locator block"},
+            },
+            RPCResult{
+                "\"hash\"         (string) The block hash of the last common "
+                "ancestor between the parameter chain and the locator\n"},
+            RPCExamples{HelpExampleCli("findforkhash",
+                                       "\"00000000c937983704a73af28acdec37b049d"
+                                       "214adbda81d7e2a3dd146f6ed09\"") +
+                        HelpExampleRpc("findforkhash",
+                                       "\"00000000c937983704a73af28acdec37b049d"
+                                       "214adbda81d7e2a3dd146f6ed09\"")},
+        }
+                                     .ToStringWithResultsAndExamples());
+    }
+
+    BlockHash hash(ParseHashV(request.params[0], "hash"));
+    std::vector<BlockHash> locatorHash(1, hash);
+
+    CBlockLocator locator(locatorHash);
+
+    LOCK(cs_main);
+
+    const CBlockIndex *ancestorIndex =
+        FindForkInGlobalIndex(::ChainActive(), locator);
+
+    return ancestorIndex->GetBlockHash().GetHex();
+}
+
 // clang-format off
 static const ContextFreeRPCCommand commands[] = {
     //  category            name                      actor (function)        argNames
     //  ------------------- ------------------------  ----------------------  ----------
+    { "blockchain",         "findforkhash",           findforkhash,           {"blockhash"} },
     { "blockchain",         "getbestblockhash",       getbestblockhash,       {} },
     { "blockchain",         "getblock",               getblock,               {"blockhash","verbosity|verbose"} },
     { "blockchain",         "getblockchaininfo",      getblockchaininfo,      {} },
diff --git a/test/functional/rpc_findforkhash.py b/test/functional/rpc_findforkhash.py
new file mode 100644
--- /dev/null
+++ b/test/functional/rpc_findforkhash.py
@@ -0,0 +1,50 @@
+#!/usr/bin/env python3
+# Copyright (c) 2020 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 findforkhash RPC."""
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import assert_equal
+
+
+class FindForkHashTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        self.num_nodes = 1
+        self.extra_args = [[]]
+
+    def setup_network(self):
+        self.setup_nodes()
+
+    def run_test(self):
+        genesis_hash = self.nodes[0].getbestblockhash()
+
+        # Create the fork block
+        self.nodes[0].generatetoaddress(
+            1, self.nodes[0].get_deterministic_priv_key().address)
+        fork_block_hash = self.nodes[0].getblockhash(
+            self.nodes[0].getblockcount())
+
+        # Create off-chain fork
+        self.nodes[0].generatetoaddress(
+            1, self.nodes[0].get_deterministic_priv_key().address)
+        off_chain_hash = self.nodes[0].getblockhash(
+            self.nodes[0].getblockcount())
+        self.nodes[0].invalidateblock(off_chain_hash)
+
+        # Off-chain block
+        assert_equal(self.nodes[0].findforkhash(
+            off_chain_hash), fork_block_hash)
+
+        # On-chain block
+        assert_equal(self.nodes[0].findforkhash(
+            fork_block_hash), fork_block_hash)
+
+        # Non-existent block
+        assert_equal(self.nodes[0].findforkhash(
+            "0cf7bb8b1697ea987f3b223ba7819250cae33efacb068d23dc24859824a77844"), genesis_hash)
+
+
+if __name__ == '__main__':
+    FindForkHashTest().main()