Home Secretary Theresa May said Mr Bristow would lead an agency of "powerful operational crime fighters".
The NCA becomes fully operational in 2013 when it takes over from the Serious Organised Crime Agency.
Its expanded role will include powers to order police forces to run operations into drugs and trafficking.
As well as replacing the Serious Organised Crime Agency (Soca), the new agency will take in the work of the Child Exploitation and Online Protection Centre (Ceop), and also house the national cyber crime unit. It will also cover border policing and economic crime.
"For too long we have lacked a strong, collaborative national response in the fight for criminal justice. The NCA will make the UK a more hostile environment for serious and organised crime and strengthen our border," Mrs May said.
She said Mr Bristow would play "a vital role" in developing the agency.
Details of an extensive policing shake-up, which included the creation of the National Crime Agency, were unveiled last year by Mrs May in a Home Office consultation paper - Policing in the 21st Century.
She described it as the "most radical reform of policing for 50 years".
Mr Bristow said he would work with the government and other crime agencies "to ensure that the NCA delivers the maximum protection possible for communities within the resources it has available".
"In partnership with other law enforcement agencies, we will ensure that criminals are identified, pursued and brought to justice, their groups dismantled and their activities disrupted. We will do even more to strip away their illegally obtained assets," he said.
Association of Chief Police Officers president Sir Hugh Orde said Mr Bristow had been chosen from "a very strong field of police leaders" to lead the NCA.
"A better co-ordinated response between the international reach and capability of this new agency and the 'eyes and ears' of local neighbourhood policing teams can help keep our streets and communities safer," Sir Hugh said.
Mr Bristow was appointed chief constable of Warwickshire Police in 2006 and chairs the G8 Law Enforcement Group.
He has been the Association of Chief Police Officers' head of crime and worked in the West Midlands Police and as director of the National Criminal Intelligence Service.
The first head of the UK's incoming National Crime Agency (NCA) will be Keith Bristow, currently chief constable of Warwickshire.