"For both sides, I think what they need to keep in mind is that there are Americans that need them, that don't really care about politics, aren't really tied up in this election and they just need some help," he said, in an interview on CNBC's "Squawk Box."
He said lawmakers on both sides of the aisle — including House Speaker Nancy Pelosi and Secretary of Treasury Steve Mnuchin — should hammer out an agreement, even if they need to tinker with it and improve upon it over time.
"Doing nothing is not the first and best option," he said.
During the coronavirus pandemic, Walmart has hired more than half a million workers to try to keep up with Americans' demand for groceries, household essentials and other items like outdoor equipment, while adjusting to a significant surge in e-commerce sales.
The big-box retailer's second-quarter sales crushed Wall Street's estimates and its online sales nearly doubled in the second quarter that ended July 31. At the time, Walmart's chief financial officer, Brett Biggs, credited government stimulus as one of the factors that gave the company's earnings a boost.
In an interview with CNBC in mid-August, Biggs declined to provide a financial outlook for the company, citing stimulus as a factor, and said Walmart was "watching what's going on in Washington, and how we're going to progress with a new stimulus package."
In recent months, McMillon said the retailer, which has stores in towns and cities across the country, has seen families cope with very different financial circumstances.
"Not everyone's in the same camp," he said. "There are people that are still being at home, who are spending money on their home and doing things to redecorate and those kinds of things. But there are other people that are struggling paycheck to paycheck – if they have a paycheck – and so many people are unemployed that we're seeing that pressure as well."
The stalemate over stimulus has created even more uncertainty as retailers, including Walmart, prepare for the holiday shopping season during a global health crisis and recession.
Walmart is among the retailers that are reimagining their approach to holiday sales and traditions — such as Black Friday — as more people shop online and the typical crowds are unsafe at a time when people are practicing social distancing.
Among the changes, Walmart is breaking up its Black Friday deals into three separate events in November, which begin on its website and continue in stores. Its stores will have pandemic-related safety measures, such as opening at 5 a.m. instead of having the midnight rush of shoppers and limiting the number of customers inside at the same time.
As shoppers look for gifts, McMillon said the world's largest retailer is still having trouble finding inventory in some merchandise categories, such as home decor and crafting.
"It's more sporadic across the store," he said. "You may find that we're not as in stock on crafts and fabrics as we should be. There have been some toys that we've been out of stock on."
McMillon said it's had better luck getting stock ahead of sales in recent weeks.
"If I could change one thing about our business right now, it would be to have an even higher in-stock level," he said. We're trying to make sure we're ready to go all the way to Christmas and beyond, but we've still got some recovery to do."
He said the spread of the coronavirus also changes shopping behavior and leads to emptier shelves at local stores in parts of the country.
"From time to time, you'll see a community that's got an increase in [Covid-19] cases and you'll see more stock-up behavior again," he said.