However, U.S. District Court Judge Edward Rafeedie declared a mistrial on two remaining counts when jurors said they could not come to a unanimous vote after 3 1/2 days of deliberations.
The trial itself lasted only four days.
Prosecutors are still deciding whether they will refile against Naughton charges of traveling across state lines in an attempt to have sex with a minor and using the Internet to set up the meeting.
They said they would base that decision on the evidence, the severity of the crime and "whether law enforcement's objectives have already been served" by the child-porn conviction.
"We're obviously very pleased with a conviction," said prosecutor Patricia Donahue.
Up to 10 years in prison?
Naughton now faces up to 10 years in jail. His lawyers said they would "absolutely" appeal the child-porn charge.
At least one jury member, meanwhile, has blamed investigators for the deadlock on the two charges, saying they arrested Naughton before they ascertained his intent.
"They screwed up," said jury foreman Stevie Brown, who has a 12-year-old daughter.
Naughton was arrested at the Santa Monica Pier on Sept. 16 after setting up a meeting with an FBI agent posing as a 13-year-old girl named "krisLA" in the dad&daughtersex chat room. Agents found images of child pornography on his computer after his arrest, images Naughton said he had been sent inadvertently through chat rooms.
When polled by Rafeedie, the jury foreman said jurors were pretty evenly split on whether to convict Naughton, voting 7-5 in favor of conviction on the traveling charge and 6-5 (with 1 undecided) on the charge of using the Internet to set up the meeting.
Dressed in a dark suit, blue shirt and bluish-gray tie -- the same outfit he wore when he took the stand -- Naughton leaned forward with his forearms and elbows on the table as the judge read the verdict, his fingers entwined in a prayerlike grip.
Though he had been stoic and composed through much of the trial, during Thursday's proceedings, Naughton clenched his jaw, blinked repeatedly and threw wide-eyed glances at his attorneys, wrinkling his forehead as he did so.
Naughton's brother 'incredulous'
After the conviction, defense attorneys scrambled to convince the judge that Naughton should remain free until his sentencing on March 6.
However, prosecutor Patricia Donahue said child pornography was considered a "crime of violence," and federal statutes required that Naughton be placed behind bars immediately.
The judge said he could allow Naughton to remain free if Donahue didn't consider him a flight risk or danger to society. But Donahue argued that the law required Naughton to be locked up, and after some consideration the judge agreed.
Naughton looked shocked as the judge ordered him to be held in a nearby jail without bail until sentencing. While waiting for U.S. marshals, Naughton shook his lawyers' hands, handed his keys and belt to his brother James, and gave him instructions on taking care of his apartment and mail while he's gone. He also took off his tie and put it on the table. Naughton had no comment as he marched out of the courtroom.
"We are very disappointed that Patrick was remanded," defense attorney Anthony Brooklier said later outside the courtroom.
After the proceedings ended, Naughton attorney Donald Marks -- who argued most of the case -- said he was glad many of the jurors believed that Naughton never intended to have sex with a minor. "We are very gratified," he said.
Holding his younger brother's belt, James Naughton flanked defense attorneys as they walked from the courtroom.
He said his family was "incredulous" about the ruling, as he clutched a cell phone to his ear in an attempt to keep his other brothers updated on the trial via a conference call. He said his brother was not prepared to go to jail.
Defense attorneys said they would appeal the child-porn count based on the assertion that the 1996 Child Porn Protection Act, or CPPA, is unconstitutional. The act is currently under review by the 9th Circuit Court of Appeals.
The CPPA, which has been challenged by the ACLU, makes it a crime to transmit digital pictures and video of "apparent" minors in sexual poses, including images that aren't real and those that depict adults who appear to be minors.
The judge wasn't as optimistic the defense strategy would work, telling Naughton's attorneys, "I don't think the defendant will get that conviction reversed."
During deliberations, jurors failed to budge for three days -- from when they first sent a note to the judge Monday indicating they were nearly evenly divided on the two undecided counts -- until Thursday, when the judge declared a mistrial.
The panel reached a decision immediately on the child-porn count, but during discussion on the other charges, deliberations escalated at times into a yelling match, according to one juror, who asked not to be named.
Naughton's core defense strategy -- that he was in a fantasy chat room and never thought "krisLA" was really only 13 -- appeared to work with at least some of the jurors.
Jury foreman: 'They screwed up'
Brown, the jury foreman, said he didn't think Naughton believed he was meeting a real 13-year-old, and he said government agents acted too soon by arresting Naughton before he actually met krisLA down on the beach.
"The government should have waited to see his intent," Brown said. "They screwed up. It happens all the time."
But another juror, a woman who asked not to be named, voted Naughton guilty on all counts, in part because he left the chat room and arranged a real-world meeting.