The "Barfi!" actor is popular with kids and will be a huge attraction for the film fest.
"Ranbir Kapoor will inaugurate the 18th Golden Elephant. His participation will be a great source of encouragement for the children," Shravan Kumar, the festival director and CEO, Children's Film Society, India, said in a statement.
Out of 900 films received from over 70 countries, the festival will showcase the best 200 children's films sourced from more than 45 countries.
The seven-day festival will see over 1.5 lakh child delegates from across the nation.
Superstar Salman Khan also extended his support to the festival. He will not be present personally, but has recorded an audio-visual tape which will be played during the festival.
"In spite of his busy schedule Salman Khan lent his support to the 18th Golden Elephant. His involvement with ICFFI will help us to reach out to the maximum number of children as they adore him," said "Stanley Ka Dabba" director Amol Gupte, who is also the chairman, Children's Film Society, India (CFSI).
The trailer of CFSI film "Gopi Gawaiya Bagha Bajaiya" which is the inaugural film at the festival, was shown at a press conference held here Monday.
The festival will have a section, 'Special Focus on Children with Special Needs', delivered through dedicated film screenings.