Donovan McNabb Invests In Virtual Autograph Company, New Way To Interact W/ Fans!

NFL legend Donovan McNabb is expanding his business portfolio and getting closer to his fans at the same time ... telling TMZ Sports he's invested in a virtual autograph company.

The former Philadelphia Eagles quarterback explained his decision to partner with FanFair Signatures -- a request-based digital keepsake outlet -- and he said it's a unique way for athletes to interact with their supporters, which could be a real game-changer.

Think Cameo ... but for digitally handwritten personalized prints.

McNabb said he loves to sign items and write personal notes for football fans ... but his packed schedule can make it hard to fulfill everyone's wishes when he's out and about.

He said FanFair simplifies that process by sending fans' requests directly to him so he can write out personal notes and his Hancock using a stylus on an app -- which then get thrown on a print and delivered to the recipients.

McNabb believes he's spearheading a movement ... and sees other athletes following his lead by joining the company in the future as well.