diff --git a/lib/installer.js b/lib/installer.js
index 5b30c6e..60f960d 100644
--- a/lib/installer.js
+++ b/lib/installer.js
@@ -23,11 +23,12 @@ const path = __importStar(require("path"));
 const semver = __importStar(require("semver"));
 const IS_WINDOWS = process.platform === 'win32';
 class DotnetCoreInstaller {
-    constructor(version) {
+    constructor(version = "", jsonfile = "") {
         if (semver.valid(semver.clean(version) || '') == null) {
             throw 'Implicit version not permitted';
         }
         this.version = version;
+        this.jsonfile = jsonfile;
     }
     installDotnet() {
         return __awaiter(this, void 0, void 0, function* () {
@@ -37,7 +38,13 @@ class DotnetCoreInstaller {
                 let escapedScript = path
                     .join(__dirname, '..', 'externals', 'install-dotnet.ps1')
                     .replace(/'/g, "''");
-                let command = `& '${escapedScript}' -Version ${this.version}`;
+                let command = `& '${escapedScript}'`;
+                if (this.version) {
+                    command += ` -Version ${this.version}`;
+                }
+                if (this.jsonfile) {
+                    command += ` -jsonfile ${this.jsonfile}`;
+                }
                 const powershellPath = yield io.which('powershell', true);
                 resultCode = yield exec.exec(`"${powershellPath}"`, [
                     '-NoLogo',
@@ -62,7 +69,14 @@ class DotnetCoreInstaller {
                     .replace(/'/g, "''");
                 fs_1.chmodSync(escapedScript, '777');
                 const scriptPath = yield io.which(escapedScript, true);
-                resultCode = yield exec.exec(`"${scriptPath}"`, ['--version', this.version], {
+                let scriptArguments = [];
+                if (this.version) {
+                    scriptArguments.concat(['--version', this.version]);
+                }
+                if (this.jsonfile) {
+                    scriptArguments.concat(['--jsonfile', this.jsonfile]);
+                }
+                resultCode = yield exec.exec(`"${scriptPath}"`, scriptArguments, {
                     listeners: {
                         stdout: (data) => {
                             output += data.toString();
diff --git a/lib/setup-dotnet.js b/lib/setup-dotnet.js
index 8822872..477f94a 100644
--- a/lib/setup-dotnet.js
+++ b/lib/setup-dotnet.js
@@ -17,6 +17,7 @@ var __importStar = (this && this.__importStar) || function (mod) {
 Object.defineProperty(exports, "__esModule", { value: true });
 const core = __importStar(require("@actions/core"));
 const installer = __importStar(require("./installer"));
+const fs = __importStar(require("fs"));
 const path = __importStar(require("path"));
 function run() {
     return __awaiter(this, void 0, void 0, function* () {
@@ -31,6 +32,15 @@ function run() {
                 const dotnetInstaller = new installer.DotnetCoreInstaller(version);
                 yield dotnetInstaller.installDotnet();
             }
+            else {
+                // Try to fall back to global.json
+                core.debug('No version found, falling back to global.json');
+                const globalJsonPath = path.join(process.cwd(), 'global.json');
+                if (fs.existsSync(globalJsonPath)) {
+                    const dotnetInstaller = new installer.DotnetCoreInstaller(undefined, globalJsonPath);
+                    yield dotnetInstaller.installDotnet();
+                }
+            }
             // TODO: setup proxy from runner proxy config
             const matchersPath = path.join(__dirname, '..', '.github');
             console.log(`##[add-matcher]${path.join(matchersPath, 'csc.json')}`);
diff --git a/src/installer.ts b/src/installer.ts
index 35cb617..8ffba22 100644
--- a/src/installer.ts
+++ b/src/installer.ts
@@ -9,11 +9,12 @@ import * as semver from 'semver';
 const IS_WINDOWS = process.platform === 'win32';
 
 export class DotnetCoreInstaller {
-  constructor(version: string) {
+  constructor(version: string = "", jsonfile: string = "") {
     if (semver.valid(semver.clean(version) || '') == null) {
       throw 'Implicit version not permitted';
     }
     this.version = version;
+    this.jsonfile = jsonfile;
   }
 
   public async installDotnet() {
@@ -24,7 +25,13 @@ export class DotnetCoreInstaller {
       let escapedScript = path
         .join(__dirname, '..', 'externals', 'install-dotnet.ps1')
         .replace(/'/g, "''");
-      let command = `& '${escapedScript}' -Version ${this.version}`;
+      let command = `& '${escapedScript}'`;
+      if (this.version) {
+        command += ` -Version ${this.version}`;
+      }
+      if (this.jsonfile) {
+        command += ` -jsonfile ${this.jsonfile}`;
+      }
 
       const powershellPath = await io.which('powershell', true);
       resultCode = await exec.exec(
@@ -54,9 +61,18 @@ export class DotnetCoreInstaller {
       chmodSync(escapedScript, '777');
 
       const scriptPath = await io.which(escapedScript, true);
+
+      let scriptArguments: string[] = [];
+      if (this.version) {
+        scriptArguments.concat(['--version', this.version]);
+      }
+      if (this.jsonfile) {
+        scriptArguments.concat(['--jsonfile', this.jsonfile]);
+      }
+
       resultCode = await exec.exec(
         `"${scriptPath}"`,
-        ['--version', this.version],
+        scriptArguments,
         {
           listeners: {
             stdout: (data: Buffer) => {
@@ -73,4 +89,5 @@ export class DotnetCoreInstaller {
   }
 
   private version: string;
+  private jsonfile: string;
 }
diff --git a/src/setup-dotnet.ts b/src/setup-dotnet.ts
index 08c817f..ffb5acf 100644
--- a/src/setup-dotnet.ts
+++ b/src/setup-dotnet.ts
@@ -1,5 +1,6 @@
 import * as core from '@actions/core';
 import * as installer from './installer';
+import * as fs from 'fs';
 import * as path from 'path';
 
 async function run() {
@@ -12,11 +13,19 @@ async function run() {
       `::warning::Use the v1 tag to get the last version, master may contain breaking changes and will not contain any required packages in the future. i.e. actions/setup-dotnet@v1`
     );
 
-    let version = core.getInput('dotnet-version');
+    let version: string = core.getInput('dotnet-version');
 
     if (version) {
       const dotnetInstaller = new installer.DotnetCoreInstaller(version);
       await dotnetInstaller.installDotnet();
+    } else {
+      // Try to fall back to global.json
+      core.debug('No version found, falling back to global.json');
+      const globalJsonPath = path.join(process.cwd(), 'global.json');
+      if (fs.existsSync(globalJsonPath)) {
+        const dotnetInstaller = new installer.DotnetCoreInstaller(undefined, globalJsonPath);
+        await dotnetInstaller.installDotnet();
+      }
     }
 
     // TODO: setup proxy from runner proxy config