The company, which makes a range of low-cost legal products aimed at small businesses and consumers, said it earned $156 million in 2011.
Its S1 filing did not include the number of shares it plans to issue or the price at which it will sell them.
New types of legal businesses have grown in popularity in recent years, as upstarts start to challenge law firms and legal research giants Westlaw and Lexis-Nexis.
Earlier this year, Lexis-Nexis acquired legal news site Law360 for an undisclosed amount.
LegalZoom plans to list itself on the New York Stock Exchange under the ticker symbol “LGZ.”