The 29-year-old was seen accompanying her boyfriend Ashton Kutcher to Rosh Hashanah holiday services last month, reported Us magazine.
"The men and women were separated during the service, but Ashton always smiled at her. They were clapping and praying. She was taking it all in," a source said.
The couple were seen arriving at the centre holding hands.
The 34-year-old actor began following the sect in 2003 with his now-estranged wife Demi Moore. The couple turned to a Kabbalah counselling centre in a bid to save their marriage after he cheated on her last year.
Kutcher is said to be determined to make his new relationship with Kunis last.