In the fight for shoppers' holiday dollars, retailers are increasingly touting perks like free shipping and easy returns.

Walmart said Tuesday it is expanding two-day shipping and in-store returns to many items sold by third parties on its website next month, just ahead of the busy holiday shopping season.

The move comes as rivals Amazon and Target have been improving their own shipping perks to persuade shoppers to pick them over the competition. When it gets down to the last minute, shoppers who procrastinate later this year will be flocking to the retailers that can get items to them fastest before Christmas.

And after all those packages have been opened, many consumers will be heading back to stores to return unwanted gifts and are looking for as painless an experience as possible. Some $90 billion worth of goods was returned last holiday season.

For the past two years, Walmart has offered free two-day shipping on millions of items on its site without a membership fee, on orders of $35 or more. This latest step will add "millions of additional items" to this perk, according to Walmart. The retailer currently has more than 75 million items available for sale on its website. It doesn't break out how many are sold by Walmart versus third parties.

The discount retailer also confirmed the steps it's taking to making returning products sold by third-party sellers even easier, which is starting to roll out this month. CNBC reported these expected changes in August.

Shoppers will now be able to print out a return label directly from Walmart's website and mail unwanted items back to sellers, the company said. Or, they can bring a package back to the services desk at Walmart locations, and Walmart will mail boxes back to sellers. Walmart said it will make this option available at all of its 4,700 stores.

"A great product return experience is a top contributor to overall customer satisfaction and repeat purchases," Scott Hilton, chief revenue officer of Walmart's e-commerce division, said in a blog post.

By comparison, Target earlier this year began offering its credit card holders free two-day shipping. The retailer's REDcard also takes 5 percent off all purchases. Target shoppers without the credit card can still receive free two-day shipping with a purchase of more than $35, similar to Walmart. Amazon offers free two-day shipping for Amazon Prime members, which costs $119 a year.

"Retailers realize they are fighting for convenience," Rod Sides, head of Deloitte's retail practice, told CNBC. "At the end of the day, they have to bring everything to you."