He promised Judge Alan Gless that he was not changing his name to avoid cops or creditors, the Associated Press reported.
He said he was doing it from the name recognition.
According to the York News-Times, the young man said that as an entrepreneur, name recognition is important and the new name is more recognizable.
He said he wanted to change is name to the T-Rex designation because it is cooler. The newspaper did not specify what line of business he is in.
Gless granted Gold's request because he went through the proper legal channels to change his name.
Tyrannosaurus Rex means tyrant lizard king in Greek.
The 23-year-old's official name is now Tyrannosaurus Rex Joseph Gold.