The deal will expand the distribution reach of Kenmore products at a time when the retailer is shutting stores following years of declining sales amid intensifying competition from Wal-Mart Stores Inc and Amazon.

Sears sells big-ticket Kenmore appliances such as refrigerators and air-conditioners only in its Sears, Kmart and Sears Hometown stores.

Sears, which flagged doubts earlier this year about its ability to remain in business, said this month it would shut 43 stores, in addition to the 150 it announced in January.

Sears' stock pared some of the early gains but was still up 14 percent, on track for its best day in about four months.

Syncing Kenmore gadgets with Alexa, which will allow users to control the gadgets with voice commands, could add to the brand's appeal.

The deal to sell Alexa-activated devices could provide a modest boost to Sears' sagging sales, Retail Metrics President Ken Perkins said.

Sears joins an increasing number of retailers and manufacturers, including Whirlpool Corp, Ford Motor Co and Starbucks, which are integrating their products with Alexa as they look to garner sales through the popular digital assistant.

Alexa controls Amazon Echo, a speaker which lets the user call a cab, order pizza or shop on Amazon among other things.

Sears' deal with Amazon could even eat into in-store sales and hit margins, warned Neil Saunders, managing director of retail at research firm GlobalData.

"It puts Sears into a marketplace that is very price competitive and where fulfillment costs are high; this is something that may be challenging for margins."

The move, nevertheless, underscores the broader trend of store-based retailers increasingly looking to sell more online.

Footwear maker Nike Inc also said last month it would start selling a limited product assortment directly on Amazon, rather than through third-party and unlicensed dealers.