She will have a three-year tenure, notification issued by the Social Justice and Empowerment Department said.
Reacting to the development, Jagruti, who had contested 2012 Assembly election against a BJP candidate, said she was never against the party.
She had joined Gujarat Parivartan Party (GPP), formed by former Chief Minister Keshubhai Patel ahead of 2012 elections. The party merged with BJP in 2014.
Jagruti had contested from Ellisbridge, her late husband's constituency, on GPP ticket in 2012, losing to BJP's Rakesh Shah.
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Asked if she would now join the ruling party, she said, "I will let you know when I take that decision."
Haren Pandya, who was a minister in Narendra Modi-led Gujarat government in 2002, was shot dead by two assailants near the Law Garden area of Ahmedabad on March 26, 2003.
Gujarat High Court later acquitted all the 12 accused arrested in the case by the CBI.