Tyler Robinson confessed to murdering Charlie Kirk in a chilling text exchange with his trans lover hours after allegedly carrying out the assassination — and left him a hidden note confessing to the plot, prosecutors said.

Less than three hours after the Sept. 10 killing, the 22-year-old told his live-in partner, Lance Twiggs, that he had been planning the killing for a week, according to an indictment filed Tuesday.

He messaged Twiggs to “drop what you are doing, look under my keyboard” after shooting Kirk from a rooftop at Utah Valley University in Orem, Utah.

Twiggs then found a note from Robinson reading, “I had the opportunity to take out Charlie Kirk and I’m going to take it,” according to the indictment.

Robinson was charged Tuesday with aggravated murder, felony discharge of a firearm causing serious bodily injury and obstruction of justice — three of the seven total counts.

The exchange alleges that Twiggs knew all about Tyler’s alleged role in the assassination more than 24 hours before he was caught.

Twiggs, whom authorities described as a male transitioning to female, immediately texted Robinson asking if it was some kind of sick joke.

“I am still ok my love, but am stuck in Orem for a little while longer yet. Shouldn’t be long until I can come home, but I gotta grab my rifle still. To be honest I had hoped to keep this secret till I died of old age. I am sorry to involve you,” Robinson allegedly wrote back.

When Twiggs asked Robinson outright if he was the one who killed Kirk, Robinson texted: “I am. I’m sorry.”

Here's the latest on the Charlie Kirk shooting in Utah

• Police identified Tyler Robinson, 22, as the alleged assassin who fatally shot Charlie Kirk at Utah Valley University on Sept. 10.
• Robinson was charged with aggravated murder, felony discharge of a firearm causing serious bodily injury and obstruction of justice.
• Law enforcement confirmed that Robinson was living with a transgender roommate, and communications between the two helped the feds catch the alleged assassin.
• Kirk, the 31-year-old Turning Point USA co-founder, was attending an event on his American Comeback Tour when he was struck in the neck by a single shot.
• President Trump was among many who have called for the assassin to receive the death penalty.
• Kirk’s body was brought to Arizona from Utah on Air Force Two, accompanied by Vice President JD Vance, and taken to Phoenix’s Hansen Mortuary Chapel.
• Kirk’s funeral, which Trump has promised to attend, is scheduled for Sept. 21 at State Farm Stadium, home of the Arizona Cardinals.
• Kirk, a rising MAGA star, is survived by his wife and two young children.

In further messages, Robinson revealed that he had stashed the gun — a scoped .30-06-caliber hunting rifle belonging to his grandfather — in the bushes where he had frantically changed clothes.

He had meant to double back and retrieve it, but the cops had the area locked down, he wrote.

“I’m worried what my old man would do if I didn’t bring back grandpas rifle … how the f— will I explain losing it to my old man,” he allegedly wrote.

Twiggs has not been charged with a crime, and authorities said he is cooperating with the investigation.

“[Y]ou are all I worry about love,” Robinson wrote to Twiggs before surrendering to law enforcement.

Prosecutors will push for the death penalty, which could be carried out via firing squad, if Robinson is convicted.

Utah Gov. Spencer Cox first brought up the intention to seek the death penalty just hours after Kirk was killed last Wednesday.

“To whoever did this, we will find you. We will try you, and we will hold you accountable to the furthest extent of the law,” Cox said — adding, “I just want to remind people that we still have the death penalty in the state of Utah.”

Robinson held “leftist ideology” and was “radicalized” online in the last few years, according to prosecutors.