According to the New York Post, the 30-year-old actress married her French journalist partner in a ceremony shortly after the arrival of their daughter Rose in September.
Scarlett Johansson and Romain Dauriac secretly married after the birth of their baby girl
A source told the newspaper, "Scarlett and Romain were married in a very intimate ceremony after the birth of their daughter. They kept the wedding a big secret because they both wanted privacy."
It had been widely speculated that the couple would marry in Romain's native Paris, but the insider revealed that the wedding took place at a secret location in the US, away from the spotlight of Hollywood, or Scarlett's home town of New York.
The notoriously private couple, who are yet to confirm their marriage, started dating in 2012 and got engaged in 2013. Scarlett reportedly said at the time that she didn't want to "rush" tying the knot, adding, "being engaged is an exciting time to enjoy and to really savour".
Scarlett Johansson sparked marriage reports when she was seen wearing a new band on her ring finger
However, the Lucy star was reportedly overheard telling a friend at a Hamptons dinner party in July that she and her fiancé would be married "very soon".
Scarlett, who turned 30 in last month, gave birth to daughter Rose in September, and a representative for the couple said they were now seeking privacy as they did not want their little girl to grow up in the spotlight.