Mila began dating actor Macaulay Culkin in 2002. 
In an interview with BlackBook magazine, she stated that marriage is "not something that's important to me". Mila said she tried her best to protect her and Macaulay's privacy, noting that "We don't talk about it to the press. It's already more high profile than I want it to be." When asked if it was difficult to stay out of the tabloids and press, Kunis responded: "I keep my personal life as personal as I physically, mentally, possibly can." Asked if that is difficult she said, "I don't care. I will go to my grave trying. It is hard, but I'll end up going to a bar that's a hole in the wall. I won't go to the 'it's-happening' place."On January 3, 2011, Mila's publicist confirmed reports that Mila and Macaulay had ended their relationship, saying "The split was amicable, and they remain close friends."

She has identified herself in interviews as a fan of the online computer game World of Warcraft and has received attention from the game's fan community as a result. She has not released what server she is in but says she is with her close friends in the Alliance In a 2008 interview with Jimmy Kimmel, she stated she had not used voice chat in the game since another player recognized her voice. Although she has described herself as a "computer nerd", she does not have a Myspace, Facebook or Twitter account. Mila discussed her desire for privacy: "Why would I want to share my life with the world when it's being shared already, without my consent? The only problem with not having an account is that there are fake accounts, pretending to quote me. But what am I going to tweet about?"


In January 2011, she revealed her struggle with an eye condition called chronic iritis that had caused blindness in one eye. However, a couple of months earlier she had surgery that corrected the problem. Mila also has the condition heterochromia iridum, where the irises have different colors. One eye is brown, and the other is green.
On September 14, 2011, the FBI announced it was investigating the alleged hacking of Mila's cellphone and email accounts, along with those of other celebrities. Christopher Chaney from Jacksonville, Florida, pleaded guilty in federal court to nine counts of computer hacking.

In November 2011, Mila was escorted by Sgt. Scott Moore to a United States Marine Corps Ball in Greenville, North Carolina. Kunis had accepted Moore's invitation in July after he posted it as a YouTube video while serving with the 3rd Battalion, 2nd Marine Regiment, in Afghanistan's Helmand province. The event celebrated the Marine Corps' 236th anniversary.