Home ministry sources said Ibrahim took over as IB director Tuesday.
Ibrahim, an IPS officer of the Madhya Pradesh cadre, has taken over from Nehchal Sandhu who retired Dec 31. He will hold the post for two years.
Ibrahim was appointed officer on special duty in IB last month after the government decided to elevate him as the head of the organisation. He was serving as special director in the IB earlier.
Sources said Ibrahim has direct experience in anti-terror operations and has handled responsibilities ranging from the Kashmir desk to cyber security cell.
In his initial career, Ibrahim had field postings in Madhya Pradesh and had encounters with dacoits of Chambal ravines.
Officials who have worked with Ibrahim describe him as a thoroughbred professional and a gentle, soft-spoken person with talent for information-gathering.
A former Research and Analysis Wing (RAW) chief said Ibrahim was "one of the finest officers".
Another former police officer who has worked with Ibrahim in the IB described him as a "soft spoken, very balanced person".
"He will make a very good DIB," the officer, who spoke on the condition of anonymity, told IANS.
The officer said Ibrahim had handled security in IB and his "heavy charter" included internal and industrial security.
Prashant Mehta, who was district magistrate in Morena when Ibrahim was a superintendent of police in the district in the early '80s, said that he had dealt well with the menace of dacoity of Chambal region during his time.
He said Ibrahim was "old school gentleman" suited to intelligence.
"He does not allow his right hand to know what the left hand is doing," Mehta said.
Mehta said that Ibrahim was officer on special duty to former union minister Madhavrao Scindia and had also served with former home minister Mufti Mohammad Sayeed.
Officials said Ibrahim had influenced thinking on terrorism and suggested that agencies need to pay greater thrust to outfits having base in the country.
They said that during his work in Jammu and Kashmir, Ibrahim laid emphasis on engagement with civil society for effectiveness of intelligence work.
Former IB chief Ajit Doval said Ibrahim would live up to the high standards of his post.
He said that references in the media to Ibrahim's religion were unwarranted.
"It is irresponsible for the media to give religious salience to the question of appointment of DIB. It is not in national interest," Doval said.
Former Research and Analysis Wing (RAW) chief A.K. Dulat said that Ibrahim had an "outstanding reputation" while he was in Madhya Pradesh and "that was a reason he got into IB".
Dulat said Ibrahim was a thoroughbred professional and was the first from the minority community to join the IB at a relatively senior level.
He agreed with the suggestion that there was need for more people from the main minority community to join the IB and said Ibrahim's elevation would serve as an inspiration.
"I am sure it would," he said.
Ibrahim's appointment comes at a politically crucial juncture as he will be head of IB during the next Lok Sabha polls scheduled for 2014.
Sources said the appointment will help counter an impression that members from the Muslim community do not make it to top posts in intelligence.