The company would be listed on NASDAQ under the ticker MKTG.
Aprimo said the price and number of shares have not been determined.
Morgan Stanley & Co. is underwriting the offering.
The IPO has been anticipated for months.
The company last year posted its seventh straight year of double-digit revenue growth, and swelled to 300 workers at its headquarters east of College Avenue on 96th Street.
Aprimo has fielded a number of industry accolades, including a top score in June from Gartner Inc.'s Magic Quadrant report for the company's "visionary" strategy.
The Stamford, Conn., market research firm had said Aprimo probably would go public and that it would benefit by being one of strongest companies in its industry.