The critically-acclaimed film, which was part of the official selection at the Cannes Film Festival, was screened before an audience of filmmakers, press and international film personalities.
Attending the festival, Kashyap told Digital Spy: "It's great. It's great to be a part of the London Indian Film Festival. Last time I was here I got distribution. I'm hoping to get the same here now. It's a fantastic turnout and a great reception for my film here in London.
"The London Indian Film Festival is lucky for me. Dev D played in year one. That Girl in Yellow Boots premiered in year two and got distribution and now I've opened the festival. It's a great platform."
Guests at the festival included Band Baaja Baaraat actress Anushka Sharma, director Michael Winterbottom, Pamela Chopra, wife of film director Yash Chopra, Senna director Asif Kapadia, star of Dekh Indian Circus Tannishtha Chatterjee, Rang Rasiya star Ferena Wazeir,7 Welcome to London actor/director Asad Shan, British-Asian model-turned-actor Upen Patel and iLL Manors star Riz Ahmed.
Speaking about Gangs of Wasseypur, Riz Ahmed told Digital Spy: "I thought it was a really exciting film. I think Indian cinema's moving into a really interesting space internationally. It's getting a much bigger audience.
"I think filmmakers like Anurag are leading the charge in bringing the world this new kind of voice. It's edgy. It's very Indian but it's also got an audience because it's so cool and so different."
Ahmed said he hoped to work with Kashyap in the future.
"We've been looking for something together for ages so let's see. If it's the right project, then I'm sure we'll work something out."
Indian rap artist and cult film director Q, whose movie Gandu is being screened at the festival, told Digital Spy why he felt it was important to have Indian cinema represented in the UK.
"It's very important," he said. "People outside of India have a very different view of Indian cinema and are distanced from what is happening out there. Showing these kind of films demonstrates to a wide audience that things In India aren't the same any more. Our cinema is very different to even five years ago."
Speaking about the launch event, festival director Cary Rajinder Sawhney said: "It's a great turnout and great to have so many celebs turning up to support the festival which is really heartening.
"We hope that audiences are going to enjoy a range of new and exciting Indian films that aren't the usual Bollywood stuff. This is something that's kick-ass. Films that arrest your mind, excite your senses and sometimes shock you."
Sawhney outlined some of the highlights in the 13 day festival which includes events and screenings taking place in venues including the Tate Modern, the ICA, the BFI Southbank, Nehru Centre, Watermans and Cineworlds Trocadero, O2, Wood Green and Wandsworth.
"Highlights of the festival include Gandu Circus which is an amazing ensemble of artists coming together for a one-off only. Susheela Rahman, Asian Dub Foundation's Steve Chandra Savale on June 21; Q, the rap artist from India who is also a cult director. We're not gonna have that happen again. That's all at the South Bank tomorrow evening and is not to be missed.
"We have a one-off screening of the film Runway by Tareque Masud who was killed last year tragically, so we have his last film about the rise of fundamentalism in Bangladesh. A really amazing film to see. We have the world premiere of Tooting Broadway which is definitely one not to be missed.
"And then we have a whole range of other films. Love stories, like A Decent Arrangement. It's a diverse range of films and I think there is much that will appeal to a broad audience who love cinema."
The two-week event will screen Bollywood films as well as regional and alternative cinema from India.
The London Indian Film Festival runs from June 20 to July 3.