Isha and Akash, 23, were appointed to the boards of Reliance Jio Infocomm Ltd and Reliance Retail Ventures Ltd, the company said in a statement here.
Ambani, the world's richest energy billionaire, has three children - Isha, Akash and Anant. While Isha and Akash are twins, youngest sibling Anant is pursuing studies in US.
Isha, who graduated from the Yale University with majors in psychology and South Asian studies in 2013, worked with global consultancy firm McKinsey in US briefly.
Akash, who graduated from Brown University with major in Economics, had been working closely with Ambani family confidant Manoj Modi on RIL's 4G telecom venture.
The two are joining around the same age as their father Mukesh, who was 24 years old when he joined RIL in 1981.
While the Ambani scions have been seen at company's annual general meetings, Akash possibly made his first appearance on a company's business deal when RIL in 2011 signed agreement in London to sell 30 per cent stake in 23 oil and gas blocks including the producing KG-D6 fields to BP plc for USD 7.2 billion.
Isha first came under public limelight as a 16-year-old when Forbes ranked her number two in a list of the world's youngest billionaire heiresses.
The two enter the long list of scions joining family businesses.
Interestingly, a few of them had a stint at McKinsey or another consulting firm or a global bank before joining the family businesses.
Nandini Piramal, daughter of Swati and Ajay Piramal, worked with McKinsey as a business analyst before joining her family concern in 2006.
Rishad Premji spent a few years at Bain & Co in London before he joined Wipro. Aditya Mittal started out in investment banking with Credit Suisse.
"At the Board Meetings held today, Reliance Jio Infocomm Limited and Reliance Retail Ventures Limited approved the appointment of Isha Ambani and Akash Ambani as Directors on their Boards," the company said in the statement.
"The Board of Reliance Retail today also appointed Adil Zainulbhai, an independent director of RIL, on its Board. Dipak Jain is already an independent director on the Board of Reliance Retail," the statement said.
Adil Zainulbhai is former chairman of McKinsey India and was appointed as an independent director on the board of RIL in December 2013.
He and Dipak Jain are also independent directors on the Board of Reliance Jio Infocomm.
RIL is India's largest private sector company with a turnover of Rs 4,46,339 crore (USD 74.5 billion) and net profit of Rs 22,493 crore (USD 3.8 billion) in 2013-14.
Its telecom arm, Reliance Jio is the only private player with Broadband Wireless Access spectrum in all the 22 telecom circles or zones of India and plans to provide fast internet connectivity as well as 4G telephony shortly.
Reliance Retail operates 1,723 stores across 148 cities in India.