Amazon(AMZN) - Get Report is miles ahead of other retailers when it comes to apps.

A new study from Millward Brown Digital found that 76% of mobile shoppers had the Amazon app on their phone. The runner up? Walmart(WMT) - Get Report , whose app was on only 33% of mobile shoppers' phones. Twenty-seven percent had eBay's(EBAY) - Get Report app, 18% had Target's(TGT) - Get Report app, and 6% had Best Buy's(BBY) - Get Report app.

Amazon's clear lead in this area demonstrates the company's prowess on mobile, which is becoming hugely important as mobile commerce continues to grow.

Over the recent holiday weekend, mobile accounted for about half of all online shopping traffic, and about a third of all sales, according to both Adobe and comScore.

"Mobile shopping is particularly popular during key holiday dates like Thanksgiving and Black Friday because phones allow shoppers to access time-constrained offers at any time wherever they may be," Forrester analyst Sucharita Mulpuru-Kodali said.

And it's not just during the holidays. In the past six months, 63% of smartphone owners had used their phones to shop on mass merchant retailer sites, according to Millward Brown.

These customers are using both mobile Web browsers and apps to shop on their phone, but apps tend to correlate with the higher-spending, more loyal customers, according to Lincoln Merrihew, Senior Vice President of Client Services Insights and Operations at Millward Brown Digital.

"A lot of people who download apps are doing so because they're loyal, and loyal people tend to spend more than unloyal people," he said. This is a theme that runs consistent with Amazon's focus on Prime, recognizing that Prime members are more loyal and spend more money on Amazon.

Consumers tend to only really use 4-6 apps on a regular basis, according to Millward Brown, so the fact that Amazon has such a high penetration rate is huge.

"It reflects their market strength," Merrihew said. "Amazon [is] an outlier in the sense that you can buy things, compare, get consumer reviews -- there's so much information consumers find relevant."

The breadth of products on Amazon's app is so expansive that it gets used like a search engine, Merrihew added. "That makes its business proposition so great that consumers have to have that app."