On 4 March 2009, he was appointed acting mayor of Yerevan, pending the 31 May municipal elections.

On 8 December 2010 he resigned as mayor, having assaulted an official, following an incident at a Plácido Domingo concert.

The official – Aram Kandayan, an employee at the President's protocol department – had asked the mayor's wife to give up her seat.

She had been sitting next to the President Serzh Sargsyan in a seat normally reserved for the Prime Minister or the Catholicos of All Armenians.

[3][4] Although not present at the concert, Beglaryan arranged to meet Kandayan after the event and assaulted the latter before he could get out of his car.