Evert and Navratilova each won 18 Grand Slam singles titles in a span from 1974 to 1991 and were among the early stars of the WTA Tour, which was founded in 1973.
They criticised WTA Tour officials considering staging the WTA Finals in Saudi Arabia in a joint story headlined: "We did not help build women's tennis for it to be exploited by Saudi Arabia."
Navratilova and Evert said they poured their hearts into building a tour "founded on equality to empower women in a male-dominated world" but added: "That work is now imperilled."
"WTA Tour officials, without adequate consultation with the players who are the very foundation of the sport, are on the verge of agreeing to stage the WTA Finals in Saudi Arabia," the players wrote. "This is entirely incompatible with the spirit and purpose of women's tennis and the WTA itself.
"We fully appreciate the importance of respecting diverse cultures and religions. It is because of this, and not despite it, that we oppose the awarding of the tour's crown jewel tournament to Riyadh."
Saudi Arabian investments in sport have been criticised as a distraction from the nation's human rights issues, notably the Saudi Public Investment Fund (PIF) backing of the LIV Golf League.
"The WTA's values sit in stark contrast to those of the proposed host," the women's legends wrote.
"Not only is this a country where women are not seen as equal, it is a country where the current landscape includes a male guardianship law that essentially makes women the property of men. A country which criminalises the LGBTQ community to the point of possible death sentences. A country whose long-term record on human rights and basic freedoms has been a matter of international concern for decades.
"Staging the WTA final there would represent not progress, but significant regression."
Evert and Navratilova cited Saudi law requiring male guardianship to marry and wives required to obey their husbands on major domestic decisions.
"The unequal status of women remains deeply embedded in Saudi law and women who actively protest this injustice risk indefinite imprisonment," the women wrote.
"We can't sit back and allow something as significant as awarding a tournament to Saudi Arabia to happen without an open, honest discussion."
Revisit values
They recommended the WTA Board, tournament and players council conduct an open session with presentations to players from human rights experts with a debate "over whether 'progress' and 'engagement' is really possible or whether staging a Saudi crown-jewel tournament would involve players in an act of 'sports-washing' merely for the sake of a cash influx."
They asked the WTA Tour to create a human rights framework and install it to protect players, fans, sponsors, workers and others.
"Without this clearly stated framework that all tournament hosts must abide by, the WTA puts its people at risk," Navratilova and Evert said.
"The WTA should revisit the values upon which it was established. We believe that those values cannot even be expressed, much less achieved, in Saudi Arabia. Taking a tournament there would represent a significant step backwards, to the detriment not just of women's sport, but women."
The Hall of Famers said the WTA must stand for human rights as long as inequality for women exists in the world.
They closed by saying: "We offer this from our experiences: A champion is carved not just from trophies, or earnings, but from the decision to surrender comfort and luxury to make hard choices and take principled stands."
