The President is expected to sign an executive order that will begin the process of building the wall as part of a raft of new immigration measures.
Last night he tweeted: "Big day planned on national security tomorrow. Among many other things, we will build the wall!"
A security wall along the Mexican border was one of Mr Trump’s key campaign pledges and is designed to stem the flow of illegal immigrants into the US.
Reports suggest that Mr Trump will also reportedly announce a temporary ban on refugees from Syria and other Muslim nations as part of his new border policy.
Who is going to pay for Trump’s wall?
Mr Trump will reportedly visit the Department of Homeland Security, where it is thought that he will order federal funds to be released to go towards the costs of the wall.
Earlier this month, Mr Trump said that the US would initially pay for the wall and that Mexico would later reimburse the costs, although he has not said how he plans to make them pay.
Throughout his campaign, Mr Trump has insisted that Mexico will pay for the wall entirely.
When he announced his Presidential bid in June 2015, he said: “I would build a great wall and nobody builds walls better than me, believe me. I’ll build them very inexpensively – I will have Mexico pay for that wall.”
Mexico has repeatedly said that it will not contribute towards the costs of the wall. WILL TRUMP BUILD THE WALL?
Donald Trump is set to announce the commencement of his border wall
President Trump's Key Moments
Wed, January 25, 2017
Our pick of the top key moments so far for the 45th President of the United States, Donald J. Trump.
1 of 9
US President Donald Trump delivers remarks after signing five executive orders related to the oil pipeline industry in the oval office of the White House in Washington, DC, USA
How long will the wall be?
The US-Mexico border is around 1,900 miles long, but Mr Trump has said that his wall will be 1,000 miles.
Last February he said: “Of the 2,000, we don’t need 2,000, we need 1,000 because we have natural barriers … and I’m taking it price per square foot and a price per square, you know, per mile.”
There is already around 700 miles of fencing along the border, with natural barriers protecting large swathes of the remainder.
Trump will reportedly sign an executive order today
There is already fencing along 700 miles of the border
How much will Trump’s wall cost?
Mr Trump has said that the wall will cost around $8 billion (£6.3bn), although wall-builder Todd Sternfeld has suggested that it is more likely to come in at $26 billion (£20.6bn).
The existing border fence cost $2.4 billion (£1.9 bn) to erect. A report released last January estimated that extending the fence across the rest of the border would cost between $15 billion (£12bn) and $25 billion (£20bn).