So far this year 111,800 people have claimed asylum in the UK - 39% arrived in a small boat, while 37% arrived by legal means before claiming asylum.
The government says its plans are aimed at reducing the number of people coming to the UK and increasing removals of people who do not have a legal right to be in the country.
The Home Office published the changes in a 30-page document and a few hours later Mahmood presented them to the House of Commons.
Under the proposals, people granted refugee status will only be allowed to stay in the country temporarily, with their status reviewed every 30 months - half the current time period.
People could be returned to their home country, when it is deemed safe to do so.
The amount of time refugees will have to be in the UK before being allowed to apply for permanent residence will be quadrupled from five years to 20.
Families with children who have been refused asylum will be offered incentives to leave but could be forcibly removed if they refuse to go voluntarily.
Asylum seekers with income or assets would have to contribute to the cost of their stay in the UK.
Mahmood told MPs this would "end the absurdity where an asylum seeker receiving £800 a month from his family and an Audi was receiving free housing at the taxpayer's expense and the courts judged we could do nothing about it".
Home Office sources have pushed back against suggestions asylum seekers could have items of sentimental value, such as wedding rings, confiscated to pay for their accommodation.
In order to make it easier to remove failed asylum seekers, the government intends to change the way the European Convention of Human Rights and Modern Slavery Act is applied.
Mahmood also threatened to stop granting visas to people from three African countries - Angola, the Democratic Republic of Congo and Namibia - unless those governments improved co-operation on deportations.
Setting out her plans for capped safe and legal routes, Mahmood said voluntary and community organisations would be given "greater involvement" in receiving and supporting new arrivals.