Sir Paul has been acting commissioner since Sir Ian Blair's departure
Sir Paul Stephenson, 55, has been appointed Metropolitan Police commissioner, beating Sir Hugh Orde, Chief Constable for Northern Ireland, into second place.
The new London police chief was front-runner in the race for the job, considered the top policing post in the UK.
Sir Paul was Sir Ian Blair's deputy when the former commissioner suddenly quit last year after concluding he did not have the support of new mayor Boris Johnson, and became acting commissioner while the appointment process went on.
He began his career with Lancashire Constabulary in 1975 and became a superintendent in 1988.
The high-flyer spent a period in research and development before taking on an operational command post in the then Royal Ulster Constabulary, a force which was still busy dealing with the threat of terrorism.
In 1994 he was appointed assistant chief constable of Merseyside with responsibility for territorial policing - the job of ensuring that there are enough officers on the beat to provide public safety and tackle crime as it happens.
During his time on Merseyside, Sir Paul oversaw initiatives on gun crime, corruption and terrorism and spearheaded some of the force's reorganisation and modernisation efforts.
His most politically sensitive role came in 1996 when Parliament granted MI5 powers to look into serious and organised crime - something the Security Service had never previously done.
This led to Sir Paul leading negotiations on the working relationship between police officers and MI5 - a precursor to the joint counter-terrorism operations that take place today.
In 1999, Sir Paul was appointed deputy chief constable of Lancashire and took the top job three years later.
During his time back at the force, he oversaw fundamental changes to the constabulary's working practices, designed to modernise the force in line with new thinking developed in the USA. He also became the national spokesman for crime at the Association of Chief Police Officers.
While he was in charge, Lancashire was consistently in the "top tier" of police performance league tables, says the Metropolitan Police.
In March 2005, Sir Paul moved to London after being made deputy commissioner in the Met.
That role, coinciding with the tenure of Sir Ian Blair, made Sir Paul the chief operating officer at New Scotland Yard, responsible for delivering the Commissioner's strategy and overseeing important areas of police modernisation such as increasing the ethnic diversity of the force.
In 2007 he joined the board of the National Policing Improvement Agency, the body set up to drive modernisation.
Sir Paul was awarded the Queen's Police Medal in 2000 and knighted in the 2008 birthday honours.
The new commissioner is no stranger to the politics of the job, having been at the right hand of Sir Ian Blair during his controversial time in charge.
Critics in some of the newspapers suggested in the run-up to his appointment that he was too close to Sir Ian to get the job.
He has also faced criticism over what the Conservatives say has been a heavy-handed operation to combat Home Office leaks, that led to the arrest of shadow immigration minister Damian Green.