The verdict comes after four Afghan men were sentenced to death and eight others were handed a 16-year jail term earlier this month for the killing of 27-year-old Farkhunda.
"You are sentenced... For negligence of duty to one year in prison," Judge Safiullah Mojaddidi told the 11 defendants, who included senior officers, while eight other policemen were found not guilty.
"This verdict is not final and the defendants have the right to appeal," the judge added.
Forty-nine people were arrested, including 19 police officers, some of whom were shown standing by and doing nothing to stop the mob in cellphone videos recorded by bystanders.
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Her killing triggered protests around Afghanistan and drew global attention to the treatment of Afghan women.
On May 6, the same court sentenced four Afghan men to death and eight others to 16 years in prison after a three-day trial broadcast live on national television.
The trial drew praise for its fast-track nature but also prompted worry over its fairness, with Human Rights Watch saying it was "very concerned" over whether due process was followed as many of the accused did not appear to have lawyers.
Farkhunda's case become a symbol of the endemic violence that women face in Afghanistan, despite reforms since the hardline Taliban regime fell in 2001.
The backlash highlighted the angst of a post-Taliban generation in Afghanistan -- where nearly two-thirds of the population is under 25 -- that is often torn between conservatism and modernity as the country rebuilds after decades of war.