The group has targeted Shia minorities and foreign tourists in the past as well. In November last year, the group had pledged support to Islamic State (ISIS).
Atleast 43 people were killed and 13 others injured when eight gunmen stormed the bus and opened fire on members of the Ismaili community on Wednesday.
Gunmen used 9mm pistols in the massacre. The attackers managed to flee after the attack.
In the past, the group has claimed several attacks including a blast near the Wagah border in November 2014 and the July 2013 attack on the compound of Pakistan's Inter-Services Intelligence (ISI) in Sukkur.
Jundullah has also claimed the several attacks on polio workers across the country.