The two umpires, who have been serving on the Emirates International Panel of ICC Umpires, have been promoted to the top level by the ICC Umpires Selection Panel.
The two umpires will replace Daryl Harper, whose existing contract expires in July, and Asoka de Silva on the panel.
"Their promotions are a result of hard work and impressive performances and will act as an inspiration to other umpires," said David Richardson, ICC's General Manager - Cricket and convener of selection panel.
40-year-old Dharmasena made his international umpiring debut in 2009 and has since umpired in two Tests, 25 ODIs and three T20Is. As a cricketer, he played 31 Tests and 141 ODIs for Sri Lanka from 1993 to 2004 in which time he took 69 and 138 wickets, respectively.
The Colombo-born former off-spinner is also a Cricket World Cup winner with Sri Lanka in 1996 and he also umpired in the ICC Cricket World Cup 2011, including the tournament opener between Bangladesh and India in Mirpur.
At 38, Kettleborough is now the youngest umpire on the panel. The Yorkshireman played 33 first-class matches from 1994 to 1999 for Middlesex and Yorkshire in the English County Championship before he was included in the England and Wales Cricket Board (ECB) panel of umpires in 2006.
Kettleborough made his international umpiring debut when he stood in the T20I between England and Australia at Old Trafford in 2009. To date, he has umpired in two Tests, 16 ODIs and two T20Is. Like Dharmasena, Kettleborough was also in the panel of 18 umpires for the ICC Cricket World Cup 2011.
Following the appointment, Dharmasena said: "I am honoured and delighted to have been selected. To umpire alongside the most respected names in this noble profession and be included on the elite panel is something I wanted to achieve ever since I started umpiring. My next target is to continue to work hard, make good decisions and justify my inclusion."
Kettleborough said: "I am delighted to have been chosen for the elite panel and I'm looking forward to the challenges ahead."
Appointments to fill the vacancies left by Dharmasena and Kettleborough on the Emirates International Panel of ICC Umpires will be made by the relevant home boards in due course.
The ICC Umpires Selection Panel is made up of David Richardson, ICC's General Manager - Cricket, ICC Chief Match Referee Ranjan Madugalle, ex-England player, coach and former first-class umpire David Lloyd and Srinivasaraghavan Venkataraghavan, the former India captain and international umpire.
Emirates Elite Panel of ICC Umpires (2011-12)