The 22-year-old American ended his campaign in triumphant style with victory at the season-ending Tour Championship in Atlanta last week where he also clinched overall FedExCup playoff honours and the $10 million jackpot.
Spieth made 21 of 25 cuts on the PGA Tour, including four runner-up spots, as his earnings for the season ballooned to $22 million because of the FedExCup bonus.
He set a record for official earnings on the U.S. circuit, his tally of $12,030,465 eclipsing the previous mark of $10,905,166 established by Vijay Singh in 2004.
Spieth is expected to claim Player of the Year honours over three rivals -- Australian Jason Day, Northern Ireland's Rory McIlroy and American Rickie Fowler -- in a vote of his peers.
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Of that trio, Day has pushed Spieth hardest in the battle for the prized accolade as he also triumphed five times on the 2014-15 PGA Tour while claiming his first major title at the PGA Championship.
Spieth, who is known for his brilliant putting and mental strength, displayed remarkable consistency as he dominated golf for most of the year. He came close to recording the first ever calendar grand slam of the four professional majors, his worst finish a tie for fourth at the British Open.
SURPRISING FORM DIP
A surprising dip in form over the past month coincided with a red-hot run by Australian Day, who won four of six events, including the PGA Championship and two of the FedExCup playoff tournaments.
That stung the highly-competitive Spieth, who made a mental adjustment as he turned things around after missing the cut in the first two FedExCup playoff events.
"I got frustrated. I missed two cuts in a row, had never done that, lost the number one ranking. I was watching Jason Day just dominate golf," said Spieth.
"I got to work, put my head down a little more than I did right after the PGA (Championship), knowing that we could still peak this week (at the Tour Championship) and that's what we did."
As for his entire 2014-15 campaign, Spieth has a great deal to savour.
"Unreal, this year was unreal," said the American. "I don't know how we sit down and figure out how to improve on it, but we are going to try to do that.
"It's the greatest season I've ever had, obviously ... we took our game on course and off course to a level that I didn't think would be possible at different times in my life.
"It gives me a lot of confidence going forward for the next 20 years. To know that if I remain healthy, that even when things are poor, we can get back to this level quickly and that's what we showed in the playoffs."
(Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Frank Pingue)
