Portas will look at the problem of empty shops and how to prevent the growth of "clone towns" dominated by chainstores.
TV star Portas, of Mary Queen of Shops and Secret Shopper fame, is due to present her findings in the autumn.
Labour has also made increasing the diversity of high street shops a priority in its current policy review.Portas's review, carried out for the Department for Business, Innovation and Skills, will involve visits to several town centres and "engagement events" with shop owners and customers.
Mary Portas said: "With town centre vacancy rates doubling over the last two years the need to take action to save our high streets has never been starker.
"I am calling on businesses, local authorities and shoppers to contribute their ideas on how we can halt this decline in its tracks and create town centres that we can all be proud of."
A report published on Monday by the Ernst & Young Item Club suggests UK high street spending will not return to pre-recession levels until 2013.
It also said consumer spending is expected to rise by only 2% a year up to 2020.
The British Retail Consortium said the review must take into consideration the interests of all retailers, whatever their size.