The Shape-up line -- popular for its toning shoes -- is a major revenue source for Skechers, which dominates the U.S. toning shoe market.
Sears is selling the products at Sears and KMart's retail stores and websites such as TheraShoe and Melrose Avenue, Skechers said in a statement.
It added that Sears had also infringed on its patents for Twinkle Toes and Z-Strap product lines.
"While we value our relationship with Sears, their actions are causing us tremendous damage, and we simply cannot let any company, let alone a company the size of Sears, infringe on our most valuable intellectual property," Philip Paccione, General Counsel of Skechers, said.
The suit, filed in the United States District Court for the Central District of California, seeks damages as well as relief for the alleged infringements and unfair competition.
Skechers shares were trading up 2 percent at $20.14 in afternoon trade on Tuesday on the New York Stock Exchange.
(Reporting by Nivedita Bhattacharjee; Editing by Saumyadeb Chakrabarty)
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