In 2020, UK regulator Ofcom found similar amounts of time spent, although its research included watching TV.
App Annie's report indicates that apps were downloaded 230 billion times in 2021, while $170bn (NZ$248bn) was spent.
TikTok was the most downloaded app worldwide, with users spending 90 percent more time there compared to 2020.
"The big screen is slowly dying as mobile continues to break records in virtually every category - time spent, downloads and revenue," said chief executive of App Annie, Theodore Krantz.
The monitoring firm predicted that, by the second half of this year, TikTok would surpass 1.5 billion monthly active users.
The average time spent on mobile apps was four hours and 48 minutes, up 30 percent from 2019, App Annie's State of Mobile report indicated.
This was calculated across ten markets, including India, Turkey, the US, Japan, Mexico, Singapore and Canada.
Users in Brazil, Indonesia and South Korea surpassed five hours per day.
Of that time, seven out of every 10 minutes was spent on social, photo and video apps, with TikTok leading the way, the report suggested.
Ad spend strong
The mobile eco-system in general remains very healthy - with two million new apps and games launched in 2021 and the number of apps earning more than $100m up by 20 percent, according to the report.
YouTube was the most popular video streaming app worldwide, clocking up more than a million downloads in 60 different countries. Netflix came second in many regions.
Mobile gaming also grew - with people spending $116bn on them. Particularly popular were what the report called hyper-casual games such as Hair Challenge, in which players have to avoid getting their hair cut, and Bridge Race, in which players collect bricks and build stairs.
Some users have complained about the number of ads in such games but app advertising generally is doing extremely well, with global spend topping $295bn last year.
This suggests that concerns that Apple's privacy crackdown would damage mobile advertising are proving unfounded.
In its iOS 14.5 update last year, iPhone users were given the option to say 'no' to having their data collected by apps.
Some of the trends spotted in the research reflected wider changes, especially in how the pandemic has altered the way people live.
For instance, people were spending a lot of time in shopping apps - more than 100 billion hours globally, with Singapore, Indonesia and Brazil growing the fastest.
There was also a huge growth of food and drink apps - such as UberEats and Grubhub.
The number of sessions on such apps grew to 194 billion in 2021, according to the research - up 50 percent on the previous year.
Health and fitness apps also saw growth, as the pandemic meant people couldn't always attend gyms or conduct group exercise classes.
And reflecting greater emphasis on mental well-being, meditation apps such as Headspace and Calm proved popular - especially with young people, with the top five most downloaded seeing a 27 percent growth in 2021.
Spending on dating apps surged past $4bn, a 95 percent increase since 2018.
And countries with apps to help handle the Covid-19 crisis, whether vaccine passports or just information tracking, saw huge take-up.
The NHS app used in England - where it acts as a record of vaccinations - was downloaded by 71 percent of the fully vaccinated population, while Malaysia's MySejahtera app saw 80 percent of this same demographic adding it to their phones.