"It was a shock because John McEnroe makes at least -150,000 (about $210,000)".
She also said she had been assured by the BBC that men and women were being paid equally for the same work, so she feels "we were not told the truth".
Navratilova also confirmed her agent will be asking for more money ahead of next year's Wimbledon.
"It's shocking", she told Panorama, adding: "It's still the good old boys network". Meanwhile, the voices of women such as Martina Navratilova (No. 1 in singles for 332 weeks) are talked over, questioned, criticized and generally ignored.
BBC Sport seemingly stood by the pay disparity between the two stars, but insisted it had nothing to do with gender.
The BBC has attempted to explain themselves, saying McEnroe's work was "a different scale, scope and time commitment". "They are simply not comparable", the spokesperson said.
Panorama said it estimated that McEnroe (59), who was crowned Wimbledon champion three times, appeared around 30 times for the BBC at Wimbledon previous year, compared to Navratilova's 10 appearances.
The gender pay gap debate was sparked with the publishing of a list of the BBC's top earners and their salaries.
The corporation said that while Navratilova is paid per appearance, has a fixed volume of work and has no contractual commitment, McEnroe is on call for the entire 13 days of the tournament, has a larger breadth of work - including radio and publicity - and has a contract that means he can not work for another British broadcaster without the BBC's permission. "I get about -15,000 (about $21,000)", Navratilova said on one of the BBC's own shows, Panorama.
The BBC Sport salary gap has been...
During the Panorama interview, Navratilova was asked whether McEnroe "does more hours", or if he's "on air longer".
'John is contracted to be on call for the BBC across the entire 13 days of the tournament.
The BBC believes her pay reflects what she is asked to do, her time commitment, her level of broadcast experience, profile and track record and expertise.
The BBC said its contract with McEnroe is "entirely different" and that he is "regarded as the face of our Wimbledon coverage". At Wimbledon 2017 her work amounted to three live match commentaries, four highlights appearances, one short video and two other short studio appearances.
It said McEnroe's pay reflected that he was considered the sport's best commentator and his contract stopped him working for another United Kingdom broadcaster without permission, adding: 'Gender isn't a factor'.