Carlos Andrade, 42, drove the Democrat eight blocks to a health club at noon Sunday, and got the tip in change for a $4.30 fare, the New York Post reported.
If he had been dishonest, he could have kept the $200 in cash in Lautenberg's wallet, which fell out of his pocket as he was getting out of the car.
Instead, Andrade, a 15-year veteran of the cab business went through the wallet looking for telephone numbers. He finally located the number of an aide to Lautenberg, who put the two men in touch.
"I love you," Lautenberg told Andrade. He then handed him one of the $100 bills as a token of thanks.
"I couldn't get back to Washington without my ID, even though everyone knows me," Lautenberg said.