US Attorney David Clay Fowlkes said he was pleased with the sentence.
"While this is not the sentence we asked for, this is a lengthy sentence," Fowlkes said outside the courthouse.
Duggar, whose lawyers sought a five-year sentence, maintains his innocence. Defence attorney Justin Gelfand said he is grateful Brooks declined to impose the full 20-year sentence requested by prosecutors.
"We'll immediately file the notice of appeal within the next 14 days," Gelfand said.
Duggar was arrested in April 2021 after a Little Rock police detective found child porn files were being shared by a computer traced to Duggar. Investigators testified that images depicting the sexual abuse of children, including toddlers, were downloaded in 2019 onto a computer at a car dealership Duggar owned.
TLC cancelled "19 Kids and Counting" in 2015 following allegations that Duggar had molested four of his sisters and a babysitter years earlier. Authorities began investigating the abuse in 2006 after receiving a tip from a family friend but concluded that the statute of limitations on any possible charges had expired.
Duggar's parents said he had confessed to the fondling and apologised. After the allegations resurfaced in 2015, Duggar apologised publicly for unspecified behaviour and resigned as a lobbyist for the Family Research Council, a conservative Christian group.
Months later, he publicly apologised for cheating on his wife and a pornography addiction, for which he then sought treatment.
In seeking a 20-year sentence, prosecutors cited the graphic images — and the ages of the children involved — as well as court testimony about the alleged abuse of Duggar's sisters.
Duggar's past behaviour "provides an alarming window into the extent of his sexual interest in children that the Court should consider at sentencing," federal prosecutors wrote in their sentencing memorandum.
"This past conduct, when viewed alongside the conduct for which he has been convicted, makes clear that Duggar has a deep-seated, pervasive, and violent sexual interest in children and a willingness to act on that interest," the court filing said.
Prosecutors also noted that Duggar's computer had been partitioned to evade accountability software that had been installed to report to his wife activity such as porn searches, according to experts.
"There is simply no indication that Duggar will ever take the steps necessary to change this pattern of behaviour and address his predilection for minor females," prosecutors wrote.
"Duggar accepts that he is before this Court for sentencing and that this Court must impose a penalty," his attorneys wrote. "That is justice. But Duggar also appeals to this Court's discretion to temper that justice with mercy."
