The Spurs striker has known the veteran midfielder since their days at West Ham and believes the west London club would be foolish to let the 34-year-old run down his contract
The 34-year-old recently scored his 200th goal for the Blues, leaving him only two goals away from becoming the club's greatest ever marksman.
Yet the club is seemingly unwilling to offer the England international an extension on his current deal, which expires at the end of the season.
"I don't know his situation at Chelsea but in my opinion he is someone you can't replace because of the amount of goals he has scored over the years," Defoe told talkSPORT. "He is a special player. He can easily go on for another two or three years.
"At the end of the day you know you are going to get goals. You know what you are going to get from Frank and goals win games.
"I'm sure Chelsea won't get rid of him. He is a special player."
The Spurs striker played with Lampard in their formative years at West Ham and he recalls how the 34-year-old's finishing was as good then as it is now.
"I was with Frank at West Ham when I was really young and, even then, his finishing was unbelievable," he added.
"He finishes like a forward. There are not many like him, he loves scoring goals and, when he gets the chances, he doesn't miss."