diff --git a/core/libs/prx/libkernel/AppMetadata/src/ParamJsonParser.cpp b/core/libs/prx/libkernel/AppMetadata/src/ParamJsonParser.cpp
index 3645c476d..4f515a105 100644
--- a/core/libs/prx/libkernel/AppMetadata/src/ParamJsonParser.cpp
+++ b/core/libs/prx/libkernel/AppMetadata/src/ParamJsonParser.cpp
@@ -95,6 +95,27 @@ std::uint32_t parseHex4(const std::string& text, std::size_t& position) {
     return value;
 }
 
+void appendRawUtf8(const std::string& text, std::size_t& position, unsigned char first, std::string& result) {
+    unsigned count;
+    std::uint32_t codepoint;
+    std::uint32_t minimum;
+    if (first >= 0xC2 && first <= 0xDF) { count = 1; codepoint = first & 0x1F; minimum = 0x80; }
+    else if (first >= 0xE0 && first <= 0xEF) { count = 2; codepoint = first & 0x0F; minimum = 0x800; }
+    else if (first >= 0xF0 && first <= 0xF4) { count = 3; codepoint = first & 0x07; minimum = 0x10000; }
+    else throw std::runtime_error("invalid UTF-8 in param.json");
+    if (count > text.size() - position) throw std::runtime_error("truncated UTF-8 in param.json");
+    for (unsigned index = 0; index < count; ++index) {
+        const auto byte = static_cast<unsigned char>(text[position + index]);
+        if ((byte & 0xC0) != 0x80) throw std::runtime_error("invalid UTF-8 continuation in param.json");
+        codepoint = (codepoint << 6) | (byte & 0x3F);
+    }
+    if (codepoint < minimum || codepoint > 0x10FFFF || (codepoint >= 0xD800 && codepoint <= 0xDFFF))
+        throw std::runtime_error("invalid UTF-8 codepoint in param.json");
+    result.push_back(static_cast<char>(first));
+    result.append(text, position, count);
+    position += count;
+}
+
 std::string parseJsonString(const std::string& text, std::size_t& position) {
     expectChar(text, position, '"');
     std::string result;
@@ -103,7 +124,11 @@ std::string parseJsonString(const std::string& text, std::size_t& position) {
         const char c = text[position++];
         if (c == '"') break;
         if (static_cast<unsigned char>(c) < 0x20) throw std::runtime_error("control character in param.json string");
-        if (c != '\\') { result.push_back(c); continue; }
+        if (c != '\\') {
+            if (static_cast<unsigned char>(c) < 0x80) result.push_back(c);
+            else appendRawUtf8(text, position, static_cast<unsigned char>(c), result);
+            continue;
+        }
         if (position >= text.size()) throw std::runtime_error("unterminated escape in param.json");
         const char escape = text[position++];
         switch (escape) {
diff --git a/core/libs/tests/ParamJsonParser.cpp b/core/libs/tests/ParamJsonParser.cpp
index 653fb6745..67d3e54ab 100644
--- a/core/libs/tests/ParamJsonParser.cpp
+++ b/core/libs/tests/ParamJsonParser.cpp
@@ -90,11 +90,34 @@ static void CheckNumberSyntax(const std::filesystem::path& path) {
     }
 }
 
+static void CheckUtf8(const std::filesystem::path& path) {
+    const std::string prefix = R"({"titleId":"PPSA00000","localizedParameters":{"en-US":{"titleName":")";
+    const std::string suffix = R"("}}})";
+    for (const auto& title : {std::string("ASCII"), std::string("\xC2\x80"), std::string("\xE3\x82\xB2\xE3\x83\xBC\xE3\x83\xA0"),
+                              std::string("\xF0\x9F\x8E\xAE"), std::string("\xF4\x8F\xBF\xBF")}) {
+        Require(ParseText(path, prefix + title + suffix).title == title, "Valid UTF-8 title changed");
+    }
+    Require(ParseText(path, prefix + R"(\uD83C\uDFAE)" + suffix).title == "\xF0\x9F\x8E\xAE", "Escaped title changed");
+    for (const auto& title : {std::string("\x80"), std::string("\xC0\xAF"), std::string("\xC1\xBF"), std::string("\xC2"),
+                              std::string("\xE0\x80\xAF"), std::string("\xED\xA0\x80"), std::string("\xE3\x82"),
+                              std::string("\xF0\x80\x80\xAF"), std::string("\xF4\x90\x80\x80"), std::string("\xF5\x80\x80\x80"),
+                              std::string("\xFE"), std::string("\xFF"), std::string("\xC2x"), std::string("\xE3\x82x")}) {
+        bool rejected = false;
+        try { ParseText(path, prefix + title + suffix); } catch (const std::exception&) { rejected = true; }
+        Require(rejected, "Accepted malformed UTF-8 title");
+    }
+    bool rejected = false;
+    try { ParseText(path, std::string("{\"") + "\x80" + R"(":0,)" + prefix.substr(1) + "Valid" + suffix); }
+    catch (const std::exception&) { rejected = true; }
+    Require(rejected, "Accepted malformed UTF-8 object key");
+}
+
 int main() {
     const auto path = std::filesystem::temp_directory_path() / ("anyps5-param-json-" +
         std::to_string(std::chrono::steady_clock::now().time_since_epoch().count()) + ".json");
     int result = 0;
     try {
+        CheckUtf8(path);
         CheckNumberSyntax(path);
         const std::pair<const char*, std::uint64_t> sizes[] = {
             {"", 0}, {"0", 0}, {"-0", 0}, {"0.25", 0}, {"0e3", 0}, {"0E+3", 0}, {"-0e-3", 0}, {"4096", 4096},
diff --git a/core/relinker/CMakeLists.txt b/core/relinker/CMakeLists.txt
index 83a29bfbb..7886acc40 100644
--- a/core/relinker/CMakeLists.txt
+++ b/core/relinker/CMakeLists.txt
@@ -202,6 +202,13 @@ if(BUILD_TESTING)
     target_include_directories(buffer_bounds_tests PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/io/include)
     add_test(NAME buffer_bounds COMMAND buffer_bounds_tests)
 
+    add_test_executable(param_json_utf8_tests
+        ${CMAKE_CURRENT_SOURCE_DIR}/../libs/tests/ParamJsonParser.cpp
+        ${CMAKE_CURRENT_SOURCE_DIR}/../libs/prx/libkernel/AppMetadata/src/ParamJsonParser.cpp)
+    target_include_directories(param_json_utf8_tests PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/../libs)
+    add_test(NAME param_json_utf8 COMMAND param_json_utf8_tests)
+    set_tests_properties(param_json_utf8 PROPERTIES TIMEOUT 20)
+
     if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
         add_test_executable(file_writer_tests
             ${CMAKE_CURRENT_SOURCE_DIR}/io/tests/FileWriterTests.cpp