An Aliyev victory is widely seen as a foregone conclusion with the Caspian state’s downtrodden opposition unable to mount a serious challenge to his authoritarian rule.
His position has also been boosted by the steady influx of petrodollars into his government’s coffers.
Opposition parties in the tightly-controlled Caucasus nation say the conditions to hold a democratic election are not in place and accused authorities of preparing to rig the vote.
They have also denounced Aliyev’s surprise — and unexplained — decision to hold the election six months ahead of schedule as aimed at shortening the campaign period and hampering the opposition’s efforts to prevent vote rigging.
The ruling Yeni Azerbaijan party has rejected the opposition’s criticism, insisting the vote will be free and fair.
Apart from the incumbent president, seven candidates are running in the poll — all low-profile personalities who have carried out little resembling an electoral campaign.
Some of them have even called on people to vote for Aliyev.
Opposition leaders say these “dummy candidates” were hand-picked by the authorities so the vote looks competitive.
– ‘Unprecedented authority’ –
Poised to secure a fourth consecutive term, Aliyev, 56, was first elected in 2003, after the death of his father Heydar Aliyev, a former KGB officer and communist-era leader who had ruled Azerbaijan with an iron fist since 1993.
He was re-elected in 2008 and 2013 in polls that were denounced by opposition parties as fraudulent.
In 2009, Aliyev amended the country’s constitution so he could run for an unlimited number of presidential terms, in a move criticised by rights advocates.
In 2016, Azerbaijan adopted fresh controversial constitutional amendments, extending the president’s term in office to seven years from five.
The changes drew criticism from Council of Europe constitutional law experts as “severely upsetting the balance of powers” and giving the president “unprecedented” authority.
Cementing his family’s decades-long grip on power, the president last year appointed his wife Mehriban Aliyeva as first vice president.
Supporters have praised the Aliyevs for turning a republic once thought of as a Soviet backwater into a flourishing energy supplier to Europe.
But critics argue they have crushed the opposition and used their power to amass a fortune that funds a lavish lifestyle for the president and his family.
Aliyev has denied accusations of rights abuses and corruption.
Monitored by international observers from the Organisation for Security and Cooperation in Europe, the polls will open at 0400 GMT and close at 1500 GMT.
Download our app and read this and other great stories on the move. Available for Android and iOS.