If you're an Amazon Prime subscriber, food delivery just got a little bit cheaper.

The e-tail giant last week announced a new addition to the list of perks that come with its $139 annual membership. In addition to free two-day shipping and access to the Prime Video catalog, subscribers now get free access to Grubhub+.

The premium Grubhub tier normally costs $9.99 per month. It includes a number of benefits, including lower service fees, 5% credit on pickup orders and $0 delivery fees on orders over $12.

Both Prime and non-Prime members will also be able to place Grubhub orders directly on the Amazon app.

But the $120/year perk won't be automatically applied to Prime accounts. Instead, users will need to seek out the benefit and activate it themselves.

Here's how to sign up.

How to get Grubhub+ free through Amazon Prime

To sign up for the benefit, you'll need to open the Amazon app or visit its desktop site. In the search bar, type in "Grubhub" and hit enter.

You will then see a banner advertising the new partnership. Click on it and you'll be taken to the page where you can link your Amazon and Grubhub accounts.

You can find the offer at this link.

The Grubhub+ membership will only last as long as you are a Prime member. When your membership ends, your benefits will also expire.

If you cancel Prime and later decide to sign back up, you'll need to repeat the process to activate your Grubhub+ perk.

Want to be a successful, confident communicator? Take CNBC's new online course Become an Effective Communicator: Master Public Speaking. We'll teach you how to speak clearly and confidently, calm your nerves, what to say and not say, and body language techniques to make a great first impression. Sign up today and use code EARLYBIRD for an introductory discount of 30% off through July 10, 2024.

Plus, sign up for CNBC Make It's newsletter to get tips and tricks for success at work, with money and in life.