Peter Fahy said the report was not an accurate reflection
Greater Manchester Police has been told it failed a woman murdered by her ex-boyfriend as a report graded it as one of the worst in England and Wales.
There were "systematic failures" in the force's care of Clare Wood, who was strangled, the Independent Police Complaints Commission (IPCC) said.
Meanwhile, a national report by the HM Inspectorate of Constabulary (HMIC) rated the force as "poor".
Chief Constable Peter Fahy said the force had made many improvements.
Greater Manchester Police (GMP) was ranked alongside Nottinghamshire and Lincolnshire as the lowest-performing of 43 forces.
It was rated poor in its handling of day-to-day crimes and the HMIC report stated confidence and satisfaction in the force was too low.
The IPCC said failings were clearly seen in the handling of Ms Wood's case.
Certain GMP officers demonstrated "a shocking lack of understanding about the nature of domestic violence", IPCC commissioner Naseem Malik said.
Shortly before Ms Wood, who had a 10-year-old daughter, was killed by her former partner George Appleton, she had alleged he had caused criminal damage, harassed her, threatened to kill her and sexually assaulted her.
Clare Wood had made several complaints to police about Appleton
The IPPC said they were concerned over how the force handled these complaints.
On one occasion, the report stated, she had called the police after Appleton, who she met on an internet dating site, had been banging on her door and refusing to leave.
The response to this call was delayed 25 times due to a lack of police patrols.
Appleton, who had a string of previous convictions for harassment and assault, was known as a dating site prowler who would use numerous networking sites to meet women.
In February 2009, a month after she reported to police that Appleton had sexually assaulted her, he strangled her and set her on fire shortly before committing suicide.
Ms Malik said: "Our investigation has shown that more could and should have been done to provide Clare with the support and protection she needed.
"But, it cannot be said the failures by Greater Manchester Police or individual officers led to her death."
Ms Malik also highlighted the death of Katie Boardman, who was stabbed by her ex-partner Brian Taylor at her home in Farnworth in October 2008.
In December last year, the IPCC found that GMP had "failed" in its dealings with Ms Boardman after it did not recognise the risk despite 11 call-outs to the couple.
Ms Malik said: "It is clear to me during the period of time covering the deaths of Clare Wood and Katie Boardman that Greater Manchester Police's response to domestic violence related incidents was not as good as it could have been."
The HMIC criticised the force for poor performance in local crime and policing, confidence and satisfaction - two out of the three categories it examined.
In its report, HMIC said GMP was "causing concern".
The HMIC report also found it was poor in satisfying the black and minority ethnic (BME) community but said it "had a plan that showed it had a clear commitment to improve".
GMP has apologised for its failings and said it was making changes.
A spokesman said one of those improvements was in the way it handled its responses to domestic violence complaints.
Responding to the HMIC report, Mr Fahy said: "It is important to note that the figures in the report are five months out-of-date and the force has had significant achievements in cutting crime and improving performance since then.
"The report attempts to capture the complexities of policing in a format the public may find useful."
The chief constable said the force aimed to provide the "best possible service" for people.