Speaking at a summit of the Adriatic Charter group, made up of Croatia, Albania and Macedonia, Mr Cheney told leaders their countries' entry would help revitalise the two Western clubs.
He praised them for reforms to meet NATO and EU eligibility and said their involvement in US-led military operations in Iraq or Afghanistan was also "a very important step".
"You who aspire to those organisations help rejuvenate it and help us re-dedicate ourselves to the basic and fundamental values of freedom and democracy," he said at the opening of the meeting in the Croatian port of Dubrovnik.
Mr Cheney held talks with Croatian Prime Minister Ivo Sanader, and his Albanian and Macedonian counterparts Sali Berisha and Vlado Buckovski.
Mr Cheney praised the three countries for their cooperation alongside NATO and US forces in Afghanistan and Iraq.
Croatia, Macedonia and Albania signed an "Adriatic Charter" with the US in May 2003 designed to facilitate their integration into NATO, which the three hope to join by 2008.
The three premiers stressed that NATO membership figured among the top priorities for their countries.
"Membership in NATO is a strategic goal of my nation. Croatia is aware that peace and security can not be achieved in isolation," Prime Minister Sanader said before the meeting, a viewed echoed by Mr Berisha.
Mr Sanader also voiced hope that during a NATO summit, to be held in Riga in November, the three countries would be given a more precise timetable for their membership in the alliance.
The three Balkan countries also voiced their readiness to take part in the global fight against terrorism.
Croatia, Albania and Macedonia are members of NATO's Partnership for Peace program, set up after the collapse of the Soviet Union and the end of communism in central and eastern Europe.
Russian relations frosty
Mr Cheney's praise for the Adriatic leaders' efforts stood in marked contrast to the stinging rebuke of Russia he delivered to Baltic and Black Sea heads of state in Vilnius on Thursday on the first stop of his five-day trip.
Mr Cheney made diplomatic waves at a time of increasingly chilly
US-Russian relations when he accused President Vladimir Putin of backsliding on democracy and using Russia's vast energy resources to "blackmail" its neighbours.
Russia brushed off Mr Cheney's remarks as "incomprehensible", but lingering tensions between the two former Cold War rivals could bode ill for a G8 summit in St Petersburg in July.
Further integration of Moscow's neighbours into Western alliances could compound its anger. Many Russians worry the US push for global democracy is really aimed at achieving dominance in what they considered their sphere of influence before the collapse of the Soviet Union in 1991.