Jonathan Ginn was sentenced to 18 months in prison and a further 18 months on licence for threatening to kill Chris Lyttle and Naomi Long and leaving a hoax device at the Alliance East Belfast office in 2013.
Chris Lyttle MLA said: “This sentence should act as a deterrent to other people from getting involved in such activity. I am glad this unpleasant episode is now at an end.
“These sorts of actions will not deter Alliance from representing the people of East Belfast. We remain committed to working with everyone to build a shared and safer future for all.
“Making threats to kill elected representatives, as well as planting a hoax device, are serious crimes that should not be taken lightly.
“Over the past few years we have seen too many young people receive convictions for getting involved in violent behaviour on our streets. I do not want to see another generation lose out on their life opportunities because they got involved in such activity.”