According to the bank's latest annual report, Mr Diamond's pay package last year included a bonus of £2.7m.
However, its highest paid executive - not identified - received £6.7m, while another was awarded £6.5m in total.
Meanwhile, Lloyds Banking Group announced eight top staff will be paid salaries and bonuses worth £16m.
Lloyds, which is 40%-owned by the UK taxpayer, revealed that the highest earner in its top eight in 2011 took home £2.8m in pay and bonuses.
Chief executive Antonio Horta-Osorio relinquished his bonus in January following a two-month leave of absence due to stress.
Lloyds made a loss of £3.5bn for the year to 31 December.
The £2.7m bonus paid to Barclays' Mr Diamond is less than half the £6.5m bonus paid to him for 2010.
The chief executive's total pay includes a £1.35m salary, a bonus of £2.7m and long-term incentives of £2.2m.
The £6.3m pay package for 2011 compares with the £9m pay and bonuses paid to Mr Diamond for the 2010 financial year.
But the BBC's business editor Robert Peston noted that Mr Diamond may actually be paid significantly more.
"Mr Diamond has been awarded the opportunity to earn £6.75m from the group's long-term incentive plan," he said.
"Some analysts will definitely therefore argue that Barclays is understating what Mr Diamond and others may end up earning."
News of the Barclays bonuses follows controversy at other High Street banks including 82%-taxpayer-owned Royal Bank of Scotland, where chief executive Stephen Hester eventually refused his £963,000 bonus.
Barclays has repeatedly defended its right to pay bonuses because it, along with competitor HSBC, were the only major banks did not need a taxpayer bailout during the financial crisis.
The annual report comes just weeks after HM Revenue and Customs ordered Barclays to pay £500m in tax it tried to avoid.