The actress, who won an Oscar at age 9 for her role in "Paper Moon," made the revelation to People.
"I like women," the 51-year-old said. "I definitely have been dating mostly women recently."
However, she said she's "not one or the other" when it comes to identifying her sexuality, and is looking forward to going "steady" with someone.
The "Rescue Me" actress added that she thinks "women are the most amazing creatures on earth," noting that they're "gentle" and "more intelligent than the men" she's recently met.
O'Neal was previously wed to tennis star John McEnroe from 1986 to 1992, and they finalized their divorce and contentious custody battle in 1994.
The former couple had three children together: Emily, 24, Sean, 38, and Kevin, 29. The latter is the author of "Our Town," a novel about O'Neal's mother, troubled actress Joanna Moore, which she's helping him promote.