The proportion of GCSEs awarded top grades has risen for the second year in a row after the biggest exam shake-up for a generation.
More than one in five (20.8%) UK GCSE entries scored one of the three top grades this year, up from 20.5% last summer.
The proportion receiving the top grades - at least a 7 or an A grade - is the highest since 2015 and marks the second year-on-year rise in a row.
The proportion of entries getting at least a 4 or a C grade is also the highest since 2015.
A total of 67.3% of UK entries scored a C/4 or above, up from 66.9% last year, according to data published by the Joint Council for Qualifications.
The lead enjoyed by girls over boys at A/7 is unchanged from last year (6.5 percentage points), while the gap at C/4 has narrowed slightly from 9.1 points to 8.8.
The number of UK entries getting C/4 or above in English and maths has increased slightly since last year.
A total of 62% of UK entries scored C/4 or above in English, up from 61.8%, while 59.6% of entries scored C/4 in maths, up from 59.4%.
Prime Minister Boris Johnson wished students luck and said: "Nothing beats hard work and effort - and the greatest reward is knowing that you've done your best."
Education Secretary Gavin Williamson wished students "all the very best", saying results day "marks the culmination of years of hard work".
Under England's exams overhaul, GCSEs have been toughened up, with less coursework, and exams at the end of the two-year courses rather than throughout.
Traditional A*-G grades have been scrapped and replaced with a 9-1 system, with 9 the highest result.
A 4 is broadly equivalent to a C grade, and a 7 broadly equivalent to an A.
Most students receiving GCSE results this summer will have been awarded numerical grades for all their subjects as almost all courses have moved to the new system.
A total of 25 subjects were awarded new grades for the first time this year.
GCSE courses are also taken by students in Wales and Northern Ireland, where there have been separate exam reforms.
Mr Williamson said: "Today is a proud day for students, teachers and parents up and down the country, and I wish them all the very best for their results.
"It should also be an exciting day. It's a day that marks the culmination of years of hard work and opens doors that can create life-changing opportunities."
Ahead of results day, school leaders raised concerns that the new GCSE courses are "demoralising" for lower-achieving students.
A poll by the Association of School and College Leaders (ASCL) of 554 members in England found that eight in 10 believe the reformed courses are having a detrimental effect on struggling students.
Geoff Barton, ASCL general secretary, said: "The findings of this survey reflect widespread concern that reformed GCSEs have sacrificed the interests of the most vulnerable students for the supposed benefits of raising the bar for the most able students."
A Department for Education spokeswoman said: "Exams are an essential part of ensuring that young people have acquired the knowledge and skills they need, but should never be at the expense of a young person's wellbeing."