The 16-year-old Keys beat Gail Brodsky 6-3 6-4 in Sunday's USTA wildcard play-off final.
In the men's final, Levine crushed the hopes of former top-20 star Robby Ginepri, taking just 84 minutes to beat him 6-0 6-2 6-1 in Georgia.
Keys, who also won a play-off to claim her place in August's US Open, said: "I'm starting to like these wildcard play-offs.
"I knew she [Brodsky] was getting pressured by my power and my serve was able to come in handy today."
Looking ahead to her trip to Melbourne in the New Year, she added: "It still hasn't hit me yet. I'm just really excited to be going to Australia. Just like the US Open, it's going to take a couple of days before it actually sinks in."
Levine, 24, admitted the ease of his win surprised even him.
"I was just in the zone today," he said. "I was just wondering after the first set if I could really stay with it. I wasn't expecting to come out like that.
"I know Robby's fit and in shape, I just didn't expect to come out like that and was wondering if I was going to be able to keep it up.
"I'm back in the 'big show' so it feels really good."