The world snooker champion is said to have been seeing the Primeval actress for several months, according to The Sun.
The pair were photographed in public together for the first time at a coffee shop near his home in Essex this week.
"They've really hit it off and Laila has been hanging out with him in his home area of Chigwell," a friend said.
O'Sullivan split from the mother of his two children, Jo Langley, in 2008, while Rouass broke up with jailed business tycoon Nasir Khan in 2007.
The sportsman has been tipped to star in the next series of Strictly Come Dancing.
Rouass was a contestant in the BBC One competition for its seventh series, where she finished inside the final four.
The former Holby City actress said in May that she would like to adopt a child.