The 19-year-old defender is expected to seal his switch to Stamford Bridge before being loaned back to the French club for the remainder of the season.
Reports suggest that Zouma will sign a five-year deal after Chelsea agreed a fee in the region of £12.5m, which would make the Blues the biggest spenders in the transfer window so far.
Zouma attracted interest from a number of clubs.
The France youth international was part of the team that won the Under-20 World Cup last year.
When asked about Zouma last week, Jose Mourinho said: “As you can see, Chelsea thinks about the future and when we think about the future.