For the first time, members of the public can check the business interests of their local police chiefs from a single webpage.
The register - made available by the College of Policing, the professional body for the service - pulls together links to information provided by each individual force.
Thirteen of the 43 forces in England and Wales state that their chief constables, deputy chief constables and assistant chief constables have "no registered business interests". The other 30 outline interests including rental properties, paid hobbies and where senior officers are also consultants or advisers in areas such as garden design, health or surveying.
Company directorships, family businesses, voluntary work - and even where police chiefs "play music in public houses and clubs for payment" - are also set out.
However, despite claims that forces are now "committed to being transparent", there are big discrepancies in the amount of information provided.
Some forces, such as the Met and West Yorkshire, name individual officers and their interests, while others - the West Midlands, Avon and Somerset - simply list interests without identifying the senior staff involved.
The webpage follows publication of the first national register of chief officer gifts and hospitality, in June, and a register of chief officer pay and reward packages, released in May.
Richard Bennett, the college's lead officer for its integrity programme, said: "The college committed itself to publishing the three registers to benefit the public - and that work is now complete. It will allow the public to view the business interests, pay, rewards and gifts and hospitality provided to chief officers across England and Wales.
"The information has been collated in one place for the first time and shows forces are committed to being more open and transparent."