Thousands of people from across the Himalayan region and 30 other countries prayed for peace, a statement from the Karmapa's office said.
"No bomb can destroy Buddha's love or blessings," it quoted the Karmapa as saying.
"It will not help if we respond to violence with more violence," it added.
On July 7 last year, 10 explosions took place inside the Buddhist shrine at Bodhgaya and other spots in the sacred town, about 100 km from Patna. Two Buddhist monks, including one from Myanmar, were wounded in the blasts.