Nazarbayev, in a speech to members of his Nur-Otan party, said: "Constitutional reforms will significantly push us towards creating a democratic, free and lawful society."
"We should all work for this party, which will for many years lead the state, the country and politics into the future. I'm saying it openly and I am not hiding this."
The oil-producing Central Asian nation has never held an election judged free and fair.
'Window dressing' reforms
The opposition, which holds just one seat in the chamber, has criticised clauses in the reform package banning electoral blocs ahead of elections and allowing Nazarbayev to become Nur-Otan's official chairman.
The amendments also raise the number of MPs to 107 from 77 and require all seats be filled from party lists, a move the opposition said would also help secure Nur-Otan's victory.
|"There are a series of steps, but I don't consider them real reforms, they are making cosmetic re-construction in order not to allow fundamental change."|
Amirzhan Kosanov, opposition leader, Social Democratic Party
Another reform lifts the limit on presidential terms, setting the stage for Nazarbayev to stay in power indefinitely.
Nazarbayev has been in power since the Soviet collapse and was re-elected in 2005 with more than 91 per cent of votes, in an election criticised by foreign observers.
The two main opposition parties, Real Ak Zhol and the Social Democratic Party, have little influence in Kazakhstan but have announced plans to run jointly.
Amirzhan Kosanov, an opposition leader, said the proposed reforms amounted to no more than window dressing.
Kosanov, from the Social Democratic Party, said: "It would be incorrect to say that elections will be democratic.
"There are a series of steps, but I don't consider them real reforms. They are making cosmetic re-construction in order not to allow fundamental change."
In his speech, Nazarbayev said party lists would be drawn up between June 22 and July 11 and said his decision to disband parliament was motivated by the "expectations of our people and of the international community".
The reforms also include allowing parties to nominate officials to the central election commission, a change proposed by the Organisation for Security and Co-operation in Europe, the continent's main democracy watchdog.
Kazakhstan is also seeking to secure the rotating chairmanship of the OSCE with the new reforms.