The popular TikToker, known as Neth Nahara, was initially sentenced by a court to six months in August.
However, an appeals court ruled that the sentence was too lenient and raised it to two years.
Ms Miguel accused the president on her TikTok account with the username @nethnahara.yaya of “anarchy and disorganisation”, local media reported.
She also blamed the president for lacking schools, housing and employment in the oil-rich southern African state.
President Lourenço was re-elected for a second term in August last year in a closely fought election that extended the ruling MPLA party’s decades-long dominance.
It has been in power since independence in 1975 and is accused of leading a repressive regime.
The appeals court in the capital, Luanda, said that Ms Miguel had used offensive words against the president, and the fact that she could influence public opinion made her conduct “more objectionable”.
She had pleaded for leniency because she was a first-time offender and a mother of young children and regretted her remarks.
But the court dismissed her plea and went further to order her to pay President Lourenço $1,200 (£1,000) for the “damage” caused to his reputation.
Judge Salomão Raimundo Kulanda described the president as “sovereign” and said the TikToker was aware of this.
Ms Miguel has over 230,000 followers on TikTok, and her videos attract thousands of views.
Her lawyer told Portuguese news outlet Lusa that this was the first time a person had been convicted in Angola for something they had posted on TikTok.
The lawyer added that the ruling was final. An appeal to the Supreme Court could not be made for a sentence that was less than three years.
The state prosecutor had asked for a harsher punishment, saying the initial six-month sentence was too “benevolent” and that Ms Miguel would likely put similar social media posts again.
Angola is one of Africa’s biggest oil exporters, but most of its people live in poverty.
It has recently been hit by a wave of protests over the rising cost of living.
