Pro golfer Jordan Spieth seen as part of the Under Armour "I Will" campaign. Photo: UA.com.

At just 22 years old, Jordan Spieth recently won yet another title at the FedEx Cup on Sept. 27. The cash bonus for the competition came in at a cool $10 million, and that's only a fraction of Spieth's wealth after a successful season and because of endorsement deals such as his signature sponsorship with Under Armour (NYSE:UAA). With winning bonuses, sponsorship and endorsement deals, and even Under Armour stock, how much could Jordan Spieth be worth now? Let's take a look.

A storied career
Spieth is young, but no newcomer on the golf scene; he's been putting up huge wins since 2009, when he won the U.S. Junior Amateur tournament at just 15 years old. He won the same title again in 2011, which won him the honor of being ranked the No. 1 PGA Junior golfer in the world. Spieth was only the second player to ever win the Juniors twice, the other being Tiger Woods. 

From there Spieth went on to play at the University of Texas, where he won the NCAA golf tournament his first year. During his second year in school, he left UT to join the PGA tour and has been working his way up through the ranks since. He first signed with Under Armour in 2013. 

Fast-forward to 2015, and he re-signed with Under Armour in a 10-year deal running through 2025. A few months after that deal was signed, he won the Valspar Championship in March, becoming the third-youngest player to do so, and then The Masters in April, and finally the U.S. Open in June. His recent FedEx Cup win is the icing on the cake of an incredibly successful season. 

Why everyone wants to be his friend
After first signing with Under Amour, Spieth signed with supplement maker BioSteel. Since then he's partnered with AT&T, Titleist, Rolex, Perfect Sense Digital, NetJets, and SuperStroke Grips. He's even appearing in commercial spots, like this one from PGATOUR.com:

It's a great play that's likely paying off for him and his sponsors, as Spieth not only gets noticed more, but also liked more. As reported in Golf Digest, Spieth's popularity continues to rise. After his first U.S. Open win, the percentage of consumers who knew Spieth's name went from 19% to 35%, and his "likability" went from 1,500th out of 3,600 celebrities to 129th. 

Even more important from an endorsement standpoint is that according to research from The Marketing Arm, Spieth is the No. 1 athlete consumers want to be like, and the No. 4 celebrity overall that people want to be like, behind Tom Hanks, Bill Gates, and Kate Middleton. This is why the study has said that Spieth has the second highest "endorsement value" of any athlete, behind only Michael Jordan. 

So what is Jordan Spieth's net worth now?
As of his most recent winning bonus of $10 million, following a successful season with $12 million in winning bonuses, Spieth is worth an estimated $30 million now.

While that is still substantially lower than some other major golf names, Spieth's value is growing rapidly, and thanks to the way his partnership with Under Armour works, he could be worth much more in the future. Under Armour re-signed Spieth in January in a 10-year deal that, while the details aren't public, appears to offer much less cash than other major golf icons such as Rory McIIroy earn. However while it's less cash, it appears to include a large portion of UA stock. As Spieth keeps winning and if shares of Under Armour climb -- they're already up around 400% since he first signed in 2013 -- Spieth stands to make even more than his bigger-cash counterparts. 

And just what is he doing with his new-found fortune? Investing in real estate, to start. In April, Spieth bought a $2.2 million estate outside Dallas. This nearly 7,400-square-foot home features an incredible swimming pool, a 288-bottle wine closet, a giant chef's kitchen with a 12-foot stone island, and a putting green outside. 

Try searching for pictures of Spieth drinking and partying, using his new fortune like many  22-year-olds might, and you won't be able to find any. So far he has been a PR person's dream, and that's just how Under Armour wants it. Under Armour looks for athletes who will be partners in their brand's growth, and for athletes who are going to work hard, win, and be well-liked. Jordan Spieth, just like basketball player Steph Curry and ballet star Misty Copeland, is the perfect fit. 

Bradley Seth McNew owns shares of Under Armour. The Motley Fool owns and recommends Under Armour. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.