Answer

Yes. In Jain tradition, Marichi was the grandson of Bhagwan Rishabhdev and the son of King Bharat Chakravarti. He is remembered as an important past birth in the life journey of Bhagwan Mahavir. ( br.dadabhagwan.org)

Explanation

Jain sources describe that Marichi took diksha in the presence of Bhagwan Rishabhdev, but later could not fully follow the strict discipline of Jain ascetic life. Because of pride in his lineage, his story became a teaching example in Jain Dharma. ( br.dadabhagwan.org)

Spiritual Understanding

His life is often remembered to show that family greatness is not enough; humility, restraint, and right conduct are what truly matter on the Jain path. ( br.dadabhagwan.org)

Takeaway

So, yes—Marichi was the grandson of Bhagwan Rishabhdev. ( br.dadabhagwan.org)