Clare's Law - named after Clare Wood, who was murdered by her ex-boyfriend in 2009 - came into force across England and Wales in March 2014.
At least 1,335 disclosures have been made so far, police figures obtained by the Press Association show.
Miss Wood's father said he was "quietly delighted" the law was being used.
The figures, released following Freedom of Information requests, show there have been at least 3,760 applications under the law so far - resulting in the 1,335 disclosures. The true totals are likely to be higher, as three police forces did not release their statistics.
The figures include both "right to ask" cases - where information was requested - and "right to know" - where police warn potential victims without being asked to do so.
Clare's Law was rolled out in March last year, following a 14-month pilot in Gwent, Wiltshire, Nottinghamshire and Greater Manchester.
Outside the four forces involved with the pilot, Lancashire had the highest number of disclosures at 146, while Norfolk had the lowest, with five.
The police figures show variation between forces in terms of the likelihood of requests being granted - more than 60% of requests in Greater Manchester led to information being released, compared with 11% in Merseyside. Hazel Blears, Labour MP for Salford and Eccles, said this suggested the law was being "applied in different ways". She also said "I will be writing to the home secretary to ask what is being done to review its use and ensure best practice is shared across the country and the right decisions are made.”
Under Clare's Law, otherwise known as the Domestic Violence Disclosure Scheme, men and women can request information about their partner, or third parties such as friends or relatives can make requests if they are "concerned".
Police and other agencies including social services then consider whether releasing information on someone's past is "necessary, lawful and proportionate" to protect someone from their partner.
Reasons for information not being released include a partner not having a record of abuse offences, or there being no "pressing need for disclosure" based on the information found.
Clare's Law does not apply in Northern Ireland, while a pilot scheme is being run in Scotland.
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