Sears Holdings Co. has appointed a veteran e-commerce executive to be the next chief marketing officer for its Sears brand.

Sears, No. 7 in the Internet Retailer Top 500, has named Monica Woo, at one point the chief marketing officer of Nutrisystem Inc. (No. 63) and a top manager at 1-800-Flowers.com Inc. (No. 45), as its next top marketing executive for the Sears brand.

Sears expects Woo to assume her new duties around mid-August. She will report to Sears Holdings chief marketing officer David Friedman, who joined Sears in September 2010 from Razorfish, a digital marketing agency. At Razorfish Friedman was president of the agency’s America’s operation. As the chief marketing officer for the Sears brand, Woo replaces Don Hamblin, who has vacated the job, the retailer says.

Woo’s appointment as chief marketing officer of the Sears format, which includes stores and online, is important on a number of fronts. Woo is another high-profile e-commerce executive taking charge of a key operation for a major chain retailer. William Lynch, the CEO of Barnes & Noble Inc. (No. 41), was appointed to the top job at that chain after previous stints as CEO of Barnes & Noble’s e-commerce operation and as the senior manager of e-commerce and an executive vice president at HSN Inc. (No. 26).

Woo also takes over the top marketing duties at Sears at a time when the retailer continues to expand in web and mobile commerce even as the company as a whole struggles. Sears hasn’t reported its second quarter earnings, but for the first quarter ended April 30, Sears saw total sales drop year over year 3.4% to $9.70 billion from $10.04 billion. Net loss for the quarter was $170 million compared to net income of $16 million in the first quarter of 2010.

Woo has a diversified e-commerce and retail executive background. Woo was formerly president of the consumer floral division at 1-800-Flowers.com and the executive vice president and chief marketing officer at Nutrisystem, a retailer of dieting products and services. Woo has also been president of Bacardi Global brands and led online banking initiatives at Citibank and Deutsche Bank. She also has worked as chief marketing and strategy officer for New York online grocer FreshDirect LLC (No. 75).

Woo’s appointment is Sears’ second major personnel announcement this week. The retailer also named Edgar Huber CEO and president for its Lands’ End apparel division. He comes from apparel retailer Liz Claiborne Inc., where he was executive vice president, global business development.