She will tell a Conservative Party conference that the system is "fundamentally broken" and is expected to promise a "firm and fair" asylum system.
The changes in the system include expediting the deportation of those "who have no claim for protection", Patel will say.
The Home Secretary said she would bring forward legislation to deliver on her commitment, in what she said would amount to "the biggest overhaul of our asylum system in decades".
"After decades of inaction by successive governments, we will address the moral, legal, practical problems with this broken system. Because what exists now is neither firm nor fair."
Patel will pledge to introduce a new asylum system that would welcome people through "safe and legal routes" and stop those arriving illegally, "making endless legal claims to remain".
This comes after it emerged this week the government has considered building an asylum processing centre in Ascension Island, a remote UK territory in the Atlantic Ocean.
Patel asked officials to look at asylum policies which had been successful in other countries, the BBC was told.
The main opposition Labour Party said the "ludicrous idea" was "inhumane, completely impractical and wildly expensive".
The promise to rebuild the asylum system comes after a record number of migrants made the journey across the English Channel to the UK in September which the Secretary has vowed to stop.
Patel said the UK would make more "immediate returns" of people who arrive illegally "and break our rules, every single week".
"And we will explore all practical measures and options to deter illegal migration."