Umar Farouk AbdulMutallab, the Nigerian man accused of trying to detonate an explosive device in his underwear aboard a Christmas 2009 flight to Detroit, pleaded guilty to all counts in court Wednesday.
He had been indicted on charges including attempted use of a weapon of mass destruction, conspiracy to commit an act of terrorism, and possession of a firearm or destructive device in furtherance of an act of violence.
AbdulMutallab had previously pleaded not guilty to the charges.
The announcement comes one day after the prosecution finished its opening statement.
On Tuesday, the prosecution finished its opening statement and the defense said it would reserve the right to give an opening statement at a later point in the trial.
The judge in the trial refused to prevent the prosecution from calling the device he allegedly carried a "bomb."
U.S. District Judge Nancy Edmunds also refused to exclude a photo of AbdulMutallab's burned genitals from the evidence.
While at previous court appearances AbdulMutallab has had outbursts - including yelling "Osama's alive," a reference to Osama bin Laden - he remained calm Tuesday.
AbdulMutallab was indicted on charges including attempted use of a weapon of mass destruction, conspiracy to commit an act of terrorism, and possession of a firearm or destructive device in furtherance of an act of violence.
He was a passenger on Northwest Airlines Flight 253 en route from the Netherlands to Detroit on Christmas Day 2009.
U.S. officials say the terror group al Qaeda in the Arabian Peninsula was behind the alleged bombing attempt.