Smith, who beat Michael van Gerwen to take the world crown last week, continued his winning run in Bahrain as he beat Gerwyn Price 8-6 to claim another trophy.
"I'm delighted," said Smith. "I've got my third World Series title and my wife told me to bring this trophy back, and I've finally got it.
"I was far from perfect tonight but I've got to take my chances when they come.
"I thought it might not be my time but I dug deep and came back. Thankfully for me, Gez missed and I managed to hit the double five.
"I've got to keep taking the rough with the smooth and keep riding this wave - hopefully it continues. I'm so happy to win this and it's been a great week to visit Bahrain for the first time."
The success was Smith's third televised title in as many months, after the Grand Slam of Darts and World Championship victories which have catapulted him up to the top of the world rankings.
The 32-year-old also took home £20,000 for winning the inaugural Bahrain event.
The attention will now turn to the Nordic Darts Masters which gets underway on January 20 in Copenhagen.