MailOnline, which includes the and sites, jumped from 24.6m unique users in May to hit a record 29.4m.
Its UK users also climbed from 7.97m in May to 8.3m in June.
Martin Clarke, MailOnline publisher, said: "Obviously we are delighted to have regained the number one spot in terms of monthly unique visitors and we are particularly pleased with the increase in UK traffic. This is the result of steady and consistent growth since the redesign of our site in May 2008.
"MailOnline's continued growth as a major player in the world news market is becoming increasingly important as we get better at monetising our overseas traffic."
dropped to second, despite boosting its own audience figures by 6.5% month on month to 28.97m and increasing its UK users from 9.94m in May to 10.2m in June.
unique users jumped by 7.6% month on month to hit 27.2m, placing the site in third spot. Its UK users rose from 8.6m in May to 9.19m in June.
maintained its position ahead of fellow News International title Times Online with a 9.22% month-on-month jump in unique users to 25.1m. Its UK users went from 8.46m in May to 8.7m.
's unique users increased by 4% month on month to hit 21.2m and its UK users rose from 7.47m in May to 7.67m in June.
Mirror Group, spanning , and , overtook Independent.co.uk for sixth spot, increasing its audience by 9% month on month to 9.4m unique users.
Its UK users also increased from 4.49m in May to 4.9 in June.
suffered a decline in unique users, dropping 2.3% to 9.35m unique users. However, its UK users increased from 3.68m in May to 3.78m in June.