The British comedian was photographed kissing the girl in a car after he left a yoga class in Los Angeles, reports The Sun.
Brand was reportedly spotted kissing a different woman after a yoga class last week.
A source said: "Russell arrived at yoga with his new girl on Tuesday and they shared a big kiss in his car after the class.
"His antics are the talk of his yoga class.
"He was spotted with a girl after his lesson last Thursday too. He had just left the class and was all over her in a nearby café."
Russell Brand has been romantically linked with a string of women in recent months following his divorce from singer Katy Perry.
Two weeks ago, he was said to have started a relationship with trainee actress Aimee Levoir at a Suffolk hotel, on the same day that Spice Girl Geri Halliwell had announced she and Brand were an item.
Brand briefly dated Mexican artist Oriela Medellin Amieiro, after meeting her at the yoga class.
In March, he was said to be involved with Hungarian model Nikolett Barabas, while he was also in a short relationship with Isabella Brewster, whom he also met at yoga.