diff --git a/doc/build-helpers/testers.chapter.md b/doc/build-helpers/testers.chapter.md
index a7741e96562b..632b11ab12ea 100644
--- a/doc/build-helpers/testers.chapter.md
+++ b/doc/build-helpers/testers.chapter.md
@@ -129,6 +129,13 @@ It has two modes:
 
   Example: `{ "include_verbatim" = true; }`
 
+`extraArgs` (list of strings, optional) {#tester-lycheeLinkCheck-param-extraArgs}
+
+: Extra command line arguments to pass to the `lychee` invocation.
+  These are passed in both the offline (build) and [`online`](#tester-lycheeLinkCheck-return) modes.
+
+  Example: `[ "--format" "json" ]`
+
 `lychee` (derivation, optional) {#tester-lycheeLinkCheck-param-lychee}
 
 : The `lychee` package to use.
diff --git a/pkgs/build-support/testers/lychee.nix b/pkgs/build-support/testers/lychee.nix
index 1976b6eb959f..493ef3e880f9 100644
--- a/pkgs/build-support/testers/lychee.nix
+++ b/pkgs/build-support/testers/lychee.nix
@@ -37,6 +37,7 @@ let
       remap ? { },
       lychee ? deps.lychee,
       extraConfig ? { },
+      extraArgs ? [ ],
     }:
     stdenv.mkDerivation (finalAttrs: {
       name = "lychee-link-check";
@@ -47,6 +48,7 @@ let
         cacert
       ];
       configFile = (formats.toml { }).generate "lychee.toml" finalAttrs.passthru.config;
+      inherit extraArgs;
 
       # These can be overridden with overrideAttrs if needed.
       passthru = {
@@ -69,13 +71,13 @@ let
             site=${finalAttrs.site}
             configFile=${finalAttrs.configFile}
             echo Checking links on $site
-            exec lychee --config $configFile $site "$@"
+            exec lychee --config $configFile ${lib.escapeShellArgs extraArgs} $site "$@"
           '';
         };
       };
       buildCommand = ''
         echo Checking internal links on $site
-        lychee --offline --config $configFile $site
+        lychee --offline --config $configFile "''${extraArgs[@]}" $site
         touch $out
       '';
     });
diff --git a/pkgs/by-name/ly/lychee/tests/network.nix b/pkgs/by-name/ly/lychee/tests/network.nix
index dcaebe7450d5..80345dc840e1 100644
--- a/pkgs/by-name/ly/lychee/tests/network.nix
+++ b/pkgs/by-name/ly/lychee/tests/network.nix
@@ -14,10 +14,21 @@ let
   check = config.node.pkgs.testers.lycheeLinkCheck {
     site = sitePkg;
   };
+  checkJson = config.node.pkgs.testers.lycheeLinkCheck {
+    site = sitePkg;
+    extraArgs = [
+      "--format"
+      "json"
+    ];
+  };
 in
 {
   name = "testers-lychee-link-check-run";
-  nodes.client = { ... }: { };
+  nodes.client =
+    { pkgs, ... }:
+    {
+      environment.systemPackages = [ pkgs.jq ];
+    };
   nodes.example = {
     networking.firewall.allowedTCPPorts = [ 80 ];
     services.nginx = {
@@ -67,5 +78,13 @@ in
     client.succeed("""
         ${lib.getExe check.online}
     """)
+
+    # EXTRA ARGS CASE: verify extraArgs are passed through to online wrapper
+
+    with subtest("extraArgs are passed to the online wrapper"):
+        client.succeed("""
+            ${lib.getExe checkJson.online} --output /tmp/lychee.json
+            jq -e .total /tmp/lychee.json
+        """)
   '';
 }