While insiders could not say where things stood in the deal-making process, they said an offer was made late last week for the Oscar-winning actress to join Holland, who was recently tapped to play the webslinging superhero, reported Variety.
Sony and Marvel had no comment on the casting.
"Cop Car" helmer has been picked to direct the film. The studios are still in the process of finding a writer to join Watts in the screenwriting process.
Kevin Feige and Amy Pascal will produce the picture, and though Holland is expected to first appear in "Captain America: Civil War" in a cameo appearance as Parker, it seems more likely that Tomei will not appear until the first "Spider-Man" film bows on July 28, 2017.