diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -642,6 +642,7 @@
 	init.cpp
 	init/common.cpp
 	invrequest.cpp
+	kernel/cs_main.cpp
 	kernel/disconnected_transactions.cpp
 	kernel/mempool_persist.cpp
 	mapport.cpp
@@ -838,6 +839,7 @@
 	#       like index/*.cpp will be removed.
 	add_library(bitcoinkernel
 		kernel/bitcoinkernel.cpp
+		kernel/cs_main.cpp
 		kernel/disconnected_transactions.cpp
 		kernel/mempool_persist.cpp
 		arith_uint256.cpp
diff --git a/src/bench/rpc_mempool.cpp b/src/bench/rpc_mempool.cpp
--- a/src/bench/rpc_mempool.cpp
+++ b/src/bench/rpc_mempool.cpp
@@ -5,6 +5,7 @@
 #include <bench/bench.h>
 #include <chainparamsbase.h>
 #include <consensus/amount.h>
+#include <kernel/cs_main.h>
 #include <kernel/mempool_entry.h>
 #include <rpc/mempool.h>
 #include <test/util/setup_common.h>
diff --git a/src/blockindex.h b/src/blockindex.h
--- a/src/blockindex.h
+++ b/src/blockindex.h
@@ -8,6 +8,7 @@
 #include <arith_uint256.h>
 #include <blockstatus.h>
 #include <flatfile.h>
+#include <kernel/cs_main.h>
 #include <primitives/block.h>
 #include <sync.h>
 #include <tinyformat.h>
@@ -16,8 +17,6 @@
 
 struct BlockHash;
 
-extern RecursiveMutex cs_main;
-
 /**
  * The block chain is a tree shaped structure starting with the genesis block at
  * the root, with each block potentially having multiple candidates to be the
diff --git a/src/chain.h b/src/chain.h
--- a/src/chain.h
+++ b/src/chain.h
@@ -13,6 +13,7 @@
 #include <consensus/params.h>
 #include <crypto/common.h> // for ReadLE64
 #include <flatfile.h>
+#include <kernel/cs_main.h>
 #include <primitives/block.h>
 #include <sync.h>
 #include <tinyformat.h>
@@ -43,8 +44,6 @@
  */
 static constexpr int64_t MAX_BLOCK_TIME_GAP = 90 * 60;
 
-extern RecursiveMutex cs_main;
-
 arith_uint256 GetBlockProof(const CBlockIndex &block);
 
 /**
diff --git a/src/kernel/cs_main.h b/src/kernel/cs_main.h
new file mode 100644
--- /dev/null
+++ b/src/kernel/cs_main.h
@@ -0,0 +1,22 @@
+// Copyright (c) 2023 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_KERNEL_CS_MAIN_H
+#define BITCOIN_KERNEL_CS_MAIN_H
+
+#include <sync.h>
+
+/**
+ * Mutex to guard access to validation specific variables, such as reading
+ * or changing the chainstate.
+ *
+ * This may also need to be locked when updating the transaction pool, e.g. on
+ * AcceptToMemoryPool. See CTxMemPool::cs comment for details.
+ *
+ * The transaction pool has a separate lock to allow reading from it and the
+ * chainstate at the same time.
+ */
+extern RecursiveMutex cs_main;
+
+#endif // BITCOIN_KERNEL_CS_MAIN_H
diff --git a/src/kernel/cs_main.cpp b/src/kernel/cs_main.cpp
new file mode 100644
--- /dev/null
+++ b/src/kernel/cs_main.cpp
@@ -0,0 +1,7 @@
+// Copyright (c) 2023 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <sync.h>
+
+RecursiveMutex cs_main;
diff --git a/src/net.h b/src/net.h
--- a/src/net.h
+++ b/src/net.h
@@ -16,6 +16,7 @@
 #include <crypto/siphash.h>
 #include <hash.h>
 #include <i2p.h>
+#include <kernel/cs_main.h>
 #include <logging.h>
 #include <net_permissions.h>
 #include <netaddress.h>
@@ -31,7 +32,6 @@
 #include <uint256.h>
 #include <util/check.h>
 #include <util/time.h>
-#include <validation.h> // For cs_main
 
 #include <atomic>
 #include <condition_variable>
diff --git a/src/node/blockstorage.h b/src/node/blockstorage.h
--- a/src/node/blockstorage.h
+++ b/src/node/blockstorage.h
@@ -10,12 +10,11 @@
 
 #include <chain.h>
 #include <fs.h>
+#include <kernel/cs_main.h>
 #include <protocol.h> // For CMessageHeader::MessageStartChars
 #include <sync.h>
 #include <txdb.h>
 
-extern RecursiveMutex cs_main;
-
 class ArgsManager;
 class BlockValidationState;
 class CBlock;
diff --git a/src/node/utxo_snapshot.h b/src/node/utxo_snapshot.h
--- a/src/node/utxo_snapshot.h
+++ b/src/node/utxo_snapshot.h
@@ -15,8 +15,6 @@
 
 struct BlockHash;
 
-extern RecursiveMutex cs_main;
-
 namespace node {
 //! Metadata describing a serialized version of a UTXO set from which an
 //! assumeutxo Chainstate can be constructed.
diff --git a/src/rpc/blockchain.h b/src/rpc/blockchain.h
--- a/src/rpc/blockchain.h
+++ b/src/rpc/blockchain.h
@@ -22,8 +22,6 @@
 struct NodeContext;
 } // namespace node
 
-extern RecursiveMutex cs_main;
-
 RPCHelpMan getblockchaininfo();
 
 /**
diff --git a/src/script/scriptcache.h b/src/script/scriptcache.h
--- a/src/script/scriptcache.h
+++ b/src/script/scriptcache.h
@@ -8,12 +8,9 @@
 #include <array>
 #include <cstdint>
 
+#include <kernel/cs_main.h>
 #include <sync.h>
 
-// Actually declared in validation.cpp; can't include because of circular
-// dependency.
-extern RecursiveMutex cs_main;
-
 class CTransaction;
 
 /**
diff --git a/src/test/mempool_tests.cpp b/src/test/mempool_tests.cpp
--- a/src/test/mempool_tests.cpp
+++ b/src/test/mempool_tests.cpp
@@ -55,7 +55,7 @@
     }
 
     CTxMemPool &testPool = *Assert(m_node.mempool);
-    LOCK2(cs_main, testPool.cs);
+    LOCK2(::cs_main, testPool.cs);
 
     // Nothing in pool, remove should do nothing:
     unsigned int poolSize = testPool.size();
diff --git a/src/test/txvalidationcache_tests.cpp b/src/test/txvalidationcache_tests.cpp
--- a/src/test/txvalidationcache_tests.cpp
+++ b/src/test/txvalidationcache_tests.cpp
@@ -135,7 +135,7 @@
 static void ValidateCheckInputsForAllFlags(
     const CTransaction &tx, uint32_t failing_flags, uint32_t required_flags,
     bool add_to_cache, CCoinsViewCache &active_coins_tip,
-    int expected_sigchecks) EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
+    int expected_sigchecks) EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
     PrecomputedTransactionData txdata(tx);
 
     MMIXLinearCongruentialGenerator lcg;
diff --git a/src/test/validation_chainstatemanager_tests.cpp b/src/test/validation_chainstatemanager_tests.cpp
--- a/src/test/validation_chainstatemanager_tests.cpp
+++ b/src/test/validation_chainstatemanager_tests.cpp
@@ -128,7 +128,7 @@
     // Create a legacy (IBD) chainstate.
     //
     Chainstate &c1 =
-        WITH_LOCK(cs_main, return manager.InitializeChainstate(&mempool));
+        WITH_LOCK(::cs_main, return manager.InitializeChainstate(&mempool));
     chainstates.push_back(&c1);
     c1.InitCoinsDB(
         /* cache_size_bytes */ 1 << 23, /* in_memory */ true,
diff --git a/src/txdb.h b/src/txdb.h
--- a/src/txdb.h
+++ b/src/txdb.h
@@ -11,6 +11,7 @@
 #include <dbwrapper.h>
 #include <flatfile.h>
 #include <fs.h>
+#include <kernel/cs_main.h>
 #include <util/result.h>
 
 #include <cstddef>
@@ -51,10 +52,6 @@
 //! Max memory allocated to coin DB specific cache (MiB)
 static constexpr int64_t MAX_COINS_DB_CACHE_MB = 8;
 
-// Actually declared in validation.cpp; can't include because of circular
-// dependency.
-extern RecursiveMutex cs_main;
-
 /** CCoinsView backed by the coin database (chainstate/) */
 class CCoinsViewDB final : public CCoinsView {
 protected:
diff --git a/src/txmempool.h b/src/txmempool.h
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -10,6 +10,7 @@
 #include <consensus/amount.h>
 #include <core_memusage.h>
 #include <indirectmap.h>
+#include <kernel/cs_main.h>
 #include <kernel/mempool_entry.h>
 #include <kernel/mempool_options.h>
 #include <policy/packages.h>
@@ -37,8 +38,6 @@
 class Chainstate;
 class Config;
 
-extern RecursiveMutex cs_main;
-
 /**
  * Fake height value used in Coins to signify they are only in the memory
  * pool(since 0.8)
diff --git a/src/validation.h b/src/validation.h
--- a/src/validation.h
+++ b/src/validation.h
@@ -25,6 +25,7 @@
 #include <flatfile.h>
 #include <fs.h>
 #include <kernel/chainstatemanager_opts.h>
+#include <kernel/cs_main.h>
 #include <node/blockstorage.h>
 #include <policy/packages.h>
 #include <script/script_error.h>
@@ -115,7 +116,6 @@
 /** Current sync state passed to tip changed callbacks. */
 enum class SynchronizationState { INIT_REINDEX, INIT_DOWNLOAD, POST_INIT };
 
-extern RecursiveMutex cs_main;
 extern GlobalMutex g_best_block_mutex;
 extern std::condition_variable g_best_block_cv;
 /** Used to notify getblocktemplate RPC of new tips. */
diff --git a/src/validation.cpp b/src/validation.cpp
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -107,20 +107,6 @@
     "each level includes the checks of the previous levels",
 };
 
-/**
- * Global state
- *
- * Mutex to guard access to validation specific variables, such as reading
- * or changing the chainstate.
- *
- * This may also need to be locked when updating the transaction pool, e.g. on
- * AcceptToMemoryPool. See CTxMemPool::cs comment for details.
- *
- * The transaction pool has a separate lock to allow reading from it and the
- * chainstate at the same time.
- */
-RecursiveMutex cs_main;
-
 GlobalMutex g_best_block_mutex;
 std::condition_variable g_best_block_cv;
 uint256 g_best_block;
diff --git a/src/validationinterface.h b/src/validationinterface.h
--- a/src/validationinterface.h
+++ b/src/validationinterface.h
@@ -6,13 +6,13 @@
 #ifndef BITCOIN_VALIDATIONINTERFACE_H
 #define BITCOIN_VALIDATIONINTERFACE_H
 
+#include <kernel/cs_main.h>
 #include <primitives/transaction.h> // CTransaction(Ref)
 #include <sync.h>
 
 #include <functional>
 #include <memory>
 
-extern RecursiveMutex cs_main;
 class BlockValidationState;
 class CBlock;
 class CBlockIndex;