2 million items are eligible for the perk including electronics, cleaning supplies, and some food items, as long as orders are more than $35. The move undercuts one of its biggest rivals: Amazon. Amazon offers free 2-day shipping to Prime members, but prime members cost $99 per year.

Walmart says there will be no fees and no enrollment process. Marc Lore CEO of Walmart said, "At a very fundamental level, we just don't believe in having to charge for a membership."

The move comes after Walmart's third quarter earnings topped analysts expectations. Walmart attributed it to increased online shopping.