Debbie Vincent, 52, was found guilty last month at Winchester Crown Court of being involved in the Europe-wide conspiracy by the Stop Huntingdon Animal Cruelty (Shac) group against Cambridge-based Huntingdon Life Sciences (HLS).
Michael Bowes, QC, prosecuting, told the jury during her trial that the protests, which targeted suppliers and customers of HLS, included falsely accusing staff members of being paedophiles and sending incendiary devices and hoax bombs.
He said the aim of the campaign was to put HLS out of business through cutting off its suppliers by creating a "climate of fear".
One target of the activists had the grave of his mother dug up and her ashes stolen.
In addition to the prison term, Judge Keith Cutler imposed a five-year anti-social behaviour order to commence on her release.