Jo Swinson, the employment relations minister, said the changes would boost the UK economy because productivity would rise with happier employees.
Under the new rules, 20 million employees across the country are entitled to ask for flexible hours, including working from home. Employers will be obliged to consider requests reasonably, and millions are expected to take advantage of the changes.
Until now, only parents and employees with other caring duties - about 10 million people - have had the right to request flexible working.
She said the new rules could involve compressed hours, where individuals do five days' work in four, staggered hours to avoid the stresses of rush hour, or working from home.
Also Read
"Employers often find that this leads to employees being much more motivated, productive, less likely to leave. So that cuts down their staff recruitment costs. It really can be a win-win," the Liberal Democrat minister said.
"We live in a globalised society, we have technology which enables us to be doing work not just from physically being there at the workplace but actually doing so at different times of the day and from different places.
"And rather than it staying stuck in a 1950s mind-set that being at work is about physically being somewhere and it's about long hours and that 'presenteeism' culture, actually it's about achieving what you're supposed to do in your job and doing that in the most effective way," she said.
But she added: "A large amount of evidence that shows flexible working is beneficial for the economy.
Neil Carberry, the CBI director for employment and skills, said business welcomed the new rules but added: "It's important to remember that the work still needs to be done, so businesses will have to manage conflicting requests effectively and they retain the right to say no where the company just can't make it work.