The number of students taking the Welsh baccalaureate rose by more than 1,500, taking the number of exams entered across Wales to 38,433.
Education Minister Jane Hutt said the results across A-levels, AS-levels and the Welsh baccalaureate were a "cause for celebration".
She said: "Whatever their future plans young people collecting their results today deserve to take time to celebrate their successes.
"Their achievements, and the skills and knowledge they have gained will be invaluable to them in the future as they continue their lifelong learning journey through education or training in university, college or the work place."
Among success stories were twin sisters Stefanie and Roxanne Taylor, pupils at Eirias High School in Colwyn Bay, who gained six straight As between them.
Stefanie will study maths at Cardiff and Roxanne, French and English at Manchester.
The most popular A and AS-level subjects were English, mathematics and biology, all of which attracted more than 2,500 entries at A level and over 3,000 entries at AS.
A growth in the number of entries at A-level and AS-level was seen for all the sciences and for mathematics and further mathematics compared with last year, with increases ranging from 2% for biology to 14% for physics.
Entries for modern foreign languages were more variable, as was also the case in England.
At A-level there was a decrease of 8% in the number of entries for French and 3% for German, although Spanish saw an increase of 17%. At AS there were reduced entries in each of these languages.
Across all subjects, those where students performed exceptionally well included chemistry (up two percentage points to 34% gaining grade A), French (up three percentage points to 34% at grade A), German (up one percentage points to 34% at grade A) and economics (up 6 percentage points to 33% at grade A).
In mathematics 44% landed an grade A while in further mathematics 56% gaining A grades.
But with record numbers of students applying for university places, admissions tutors are warning of a competition for places.
The UK government has announced an extra 10,000 places on some courses but with an additional 40,000 applications to universities across the UK this year the system has never been under greater pressure.
Research by BBC Radio Cymru found applications for the next academic year were up in 10 different colleges and universities in Wales.
Dr Hywel Davies, director of admissions and recruitment at Aberystwyth University, said some students would be disappointed.
"If people do have more than one iron in the fire, more than one option, I would urge them to be flexible, take advice from school from careers - and who knows that the situation may be like next year.
"Take the gap year and see what happens next year."
Specialist, local Careers Wales advisers will be available to give interviews and tips regarding young people's next steps following exam results.
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