Anti-establishment candidate Bassirou Diomaye Faye, 44, swept to victory in Dakar on a promise of major reform, backed by a new generation of voters and politicians.
Faye and his mentor and now prime minister Ousmane Sonko were only released from prison 10 days before the March 24 vote.
In Cameroon, where 91-year-old Paul Biya has been in power for more than 40 years, social media has been flooded with stinging comparisons.
"Faye was two years old when Paul Biya became president" is one of the favorite slogans, often illustrated by photos of the almost juvenile-looking Faye next to Biya's worn features.
International NGOs accuse Biya's regime of systematically suppressing opposition.
Amnesty International last year accused the regime of using military tribunals to arbitrarily detain the opposition, civilians, journalists and civil society figures on the pretext that they had committed terrorist acts.
Biya's 81-year-old neighbor Teodoro Obiang Nguema Mbasogo holds the longevity record, after 44 years in power in Equatorial Guinea.
In stark contrast, half the population of Africa was under the age of 19 in 2021, according to the United Nations. The same year, the average age of the continent's heads of state was 66, Jeune Afrique magazine reported.
In Cameroon, state radio and television kept news of the Senegal election results to a minimum, but independent media were quick to detail the glaring political differences between the two nations.
"Senegal speaks to those who work behind the scenes for the dictatorship... to those pretentious zealots... who subdue the opposition... those judges who inflict arbitrary sentences. But the wheel turns," warned editorialist Aristide Mono on Cameroon's Equinoxe Radio.
In Chad, transitional President Mahamat Idriss Deby Itno sent his congratulations "to the Senegalese people for having given a real lesson of maturity and democracy to the rest of the world."
The army proclaimed him leader of a junta at the age of 37 when his father died in 2021, after three decades in charge.
The son is almost guaranteed to win May 6 elections after putting down all opposition.
His leading opponent, Yaya Dillo, was shot dead by soldiers at the end of February. Dillo's party said he had been shot through the head at close range.
"If Diomaye and Sonko were Chadian, they would have long been dead," opposition figure Avocksouma Djona Atchenemou told AFP.
'Dictators'
Faye's win "inspires and sets you dreaming but it came at great cost... because the political struggle in French-speaking Africa requires endurance and coherence, the only weapons to defeat the armoury of dictators backed by former colonial powers," another Chadian opposition figure, Max Kemkoye, told AFP.
"Congratulations to the Nelson Mandela of Senegal! They left prison and directly won the election," wrote an impressed Chadian on Facebook.
"Bassirou Faye would never have had a chance in Benin," Nourou Dine Saka Saley, of The Democrats party, said in a video posted on TikTok.
"Everyone dreams of doing the same in our countries," he added.
Benin was once known as a thriving multi-party democracy, but President Patrice Talon, 65, has been accused of becoming increasingly authoritarian after nearly eight years in office.
In Togo, President Faure Gnassingbe is under opposition pressure over attempts to impose a new constitution they fear will further prolong his time in office.
Togo's presidency late Wednesday announced more consultations were needed and suspended April 20 legislative and regional elections without setting a new date.
"I am sure that the people of Togo will be free one day like in Senegal, but we will have to fight," said Akouwa Avligan, a pharmacist in her 30s in the capital Lome.
Gnassingbe took over from his father, who died in 2005 after ruling with an iron fist for 38 years.
Faye's triumph "is a strong reminder that Africa needs a young generation of leaders, not the (Yoweri) Museveni generation who are tired and despots," Uganda's main opposition leader Bobi Wine, aka Robert Kyagulanyi, told AFP on Thursday.
"Events in Senegal have energized us to remove from power dictator Museveni by the ballot," the 42-year-old added.
Museveni, who is 79 and has ruled Uganda for more than 38 years, appears to be lining up one of his sons to succeed him.
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