Escobar took the exam earlier in the week in Miami.
"The greatest thing that can happen to you is to be a citizen of this great country," Escobar said Sunday through a translator.
Escobar fled Cuba in 2004 at age 21, leaving on a boat. He said giving up his Cuban citizenship was difficult, "but I also know this is the country that is providing for me now and in the future."
Escobar said the toughest part of the process was studying for the test. He said he learned about the Civil War and World War II in preparation.
"The time was now. I'm going to be a guy with 10 years in the big leagues. My two kids are U.S. citizens, too. We thought it was the appropriate time to take that next step," he said.