diff --git a/src/kit/index.ts b/src/kit/index.ts
index 9a91fff321..607b237ed4 100644
--- a/src/kit/index.ts
+++ b/src/kit/index.ts
@@ -1,4 +1,4 @@
-export { defineNitroPreset } from "./preset";
+export { defineNitroPreset, getDefaultNodeVersion } from "./preset";
 export { defineNitroModule } from "./module";
 
 export { writeFile, isDirectory } from "./fs";
diff --git a/src/kit/preset.ts b/src/kit/preset.ts
index 8a10b39740..b5603783ed 100644
--- a/src/kit/preset.ts
+++ b/src/kit/preset.ts
@@ -15,3 +15,41 @@ export function defineNitroPreset<
   }
   return { ...preset, _meta: meta } as P & { _meta: M };
 }
+
+const DEFAULT_NODE_VERSION = 20 as const;
+
+/**
+ * Builder to get the default Node.js version for a provider.
+ *
+ * Ideally, all presets will support Nitro's preferred `DEFAULT_NODE_VERSION`,
+ * which will simply be converted to a preset-specific identifier.
+ * If not, it will return the highest supported version below `DEFAULT_NODE_VERSION`.
+ *
+ * @param supportedNodeVersions - A set of Node.js version numbers supported by the provider.
+ * @param getNodeVerisonString  - A preset-specific function to convert a Node.js version number to the runtime string. Defaults to String constructor.
+ * @returns The Node.js version identifier for preset.
+ */
+export function getDefaultNodeVersion(
+  supportedNodeVersions: Set<number>,
+  getNodeVerisonString: (version: number) => string = String
+): string {
+  // Get Nitro's current default Node.js version
+  let version = DEFAULT_NODE_VERSION;
+
+  // Check it is supported by the provider
+  if (supportedNodeVersions.has(version)) {
+    // If so, return the mapped version
+    return getNodeVerisonString(version);
+  }
+
+  // Else, return the latest supported version
+  while (version > 10) {
+    version--;
+    if (supportedNodeVersions.has(version)) {
+      // Found the next-highest supported version
+      return getNodeVerisonString(version);
+    }
+  }
+
+  throw new Error("No supported Node.js version found");
+}
diff --git a/src/presets/azure/utils.ts b/src/presets/azure/utils.ts
index b6fba139bb..24e3cb65f7 100644
--- a/src/presets/azure/utils.ts
+++ b/src/presets/azure/utils.ts
@@ -1,9 +1,9 @@
 import { createWriteStream } from "node:fs";
-import fsp from "node:fs/promises";
 import archiver from "archiver";
-import { writeFile } from "nitropack/kit";
+import { getDefaultNodeVersion, writeFile } from "nitropack/kit";
 import type { Nitro } from "nitropack/types";
 import { join, resolve } from "pathe";
+import { readPackageJSON } from "pkg-types";
 
 export async function writeFunctionsRoutes(nitro: Nitro) {
   const host = {
@@ -49,22 +49,18 @@ export async function writeSWARoutes(nitro: Nitro) {
     version: "2.0",
   };
 
-  // https://learn.microsoft.com/en-us/azure/azure-functions/functions-reference-node?tabs=typescript%2Cwindows%2Cazure-cli&pivots=nodejs-model-v4#supported-versions
-  const supportedNodeVersions = new Set(["16", "18", "20"]);
-  let nodeVersion = "18";
-  try {
-    const currentNodeVersion = JSON.parse(
-      await fsp.readFile(join(nitro.options.rootDir, "package.json"), "utf8")
-    ).engines.node;
-    if (supportedNodeVersions.has(currentNodeVersion)) {
-      nodeVersion = currentNodeVersion;
-    }
-  } catch {
-    const currentNodeVersion = process.versions.node.slice(0, 2);
-    if (supportedNodeVersions.has(currentNodeVersion)) {
-      nodeVersion = currentNodeVersion;
-    }
-  }
+  /** @link https://learn.microsoft.com/en-us/azure/azure-functions/functions-reference-node?tabs=typescript%2Cwindows%2Cazure-cli&pivots=nodejs-model-v4#supported-versions */
+  const supportedNodeVersions = new Set([16, 18, 20]);
+
+  // Read package.json to get the current node version
+  const packageJSONPath = join(nitro.options.rootDir, "package.json");
+  const packageJSON = await readPackageJSON(packageJSONPath);
+  const currentNodeVersion = Number.parseInt(packageJSON.engines?.node);
+  /* If current node version is supported, use it,
+      otherwise use the default node version */
+  const nodeVersion = supportedNodeVersions.has(currentNodeVersion)
+    ? currentNodeVersion
+    : getDefaultNodeVersion(supportedNodeVersions);
 
   // Merge custom config into the generated config
   const config = {
diff --git a/src/presets/firebase/utils.ts b/src/presets/firebase/utils.ts
index 9e1501051e..8b291bfe8e 100644
--- a/src/presets/firebase/utils.ts
+++ b/src/presets/firebase/utils.ts
@@ -1,10 +1,16 @@
 import { existsSync } from "node:fs";
-import { writeFile } from "nitropack/kit";
+import { writeFile, getDefaultNodeVersion } from "nitropack/kit";
 import type { Nitro } from "nitropack/types";
 import { join, relative } from "pathe";
 import { readPackageJSON, writePackageJSON } from "pkg-types";
 import type { FirebaseFunctionsOptions } from "./types";
 
+/**
+ * Supported Node.js versions for Firebase Functions.
+ * @link https://cloud.google.com/functions/docs/runtime-support#node.js
+ */
+const supportedNodeVersions = new Set([18, 20]);
+
 export async function writeFirebaseConfig(nitro: Nitro) {
   const firebaseConfigPath = join(nitro.options.rootDir, "firebase.json");
   if (existsSync(firebaseConfigPath)) {
@@ -51,7 +57,7 @@ export async function updatePackageJSON(nitro: Nitro) {
       // https://cloud.google.com/functions/docs/concepts/nodejs-runtime
       node:
         (nitro.options.firebase as FirebaseFunctionsOptions)?.nodeVersion ||
-        "20",
+        getDefaultNodeVersion(supportedNodeVersions),
     },
   });
 }