Mr Sarkozy said he raised concerns over human rights with Mr Nazarbayev
France and Kazakhstan have signed energy and business deals worth $6bn (£3.8bn) during a visit to Astana by French President Nicolas Sarkozy.
Kazakhstan also agreed to allow French military supplies to pass through on their way to Afghanistan.
Mr Sarkozy said he discussed concerns over Kazakhstan's rights record with President Nursultan Nazarbayev but had not come to "give lessons".
Kazakhstan has large oil and gas fields and is Central Asia's largest economy.
Mr Nazarbayev has ruled since the country gained its independence when the Soviet Union broke up in 1991.
Kazakhstan is being courted by a number of Western nations for its energy reserves and strategic position. It shares borders with China and Russia and is near Afghanistan.
'Choice for peace'
The biggest deal was signed between Total and GDF Suez and Kazakh state energy firm Kazmunaigaz to develop the Khvalynskoye Caspian Sea gas field.
The French firms are taking a 25% stake while Kazmunaigaz retains 25%. The other 50% is owned by Russian energy giant Lukoil.
Meanwhile, construction consortium Spie Capag signed memorandums to build a pipeline that will link the giant Kashagan oil field to the Caspian Sea, circumventing Russian supply routes to Europe.
Other agreements included a plan for train conglomerate Alstom to help build a tramway in the capital, Astana, and for Thales to supply the Kazakh army with radios.
The business deals come despite criticisms from rights groups that Kazakhstan flouts basic democratic rights.
Despite the criticism of its rights record, Kazakhstan is set to become the first former Soviet republic to chair the Organisation for Security and Cooperation in Europe - an intergovernmental trans-Atlantic security and democracy body.
Mr Sarkozy gave his backing to Kazakhstan's chairmanship, saying "it is a choice for peace".
He said he had raised his concerns over human rights in Kazakhstan with Mr Nazarbayev.
"The best way to resolve problems, and there are problems and I have talked to the president, is not necessarily to come and give lessons," said Mr Sarkozy in a news conference with Mr Nazarbayev.
Kazakhstan's constitution was amended in 2007 to remove the limits on how many terms the president can remain in office.