Francisco Madeira, head of AMISOM, lauded the maturity with which the federal state held its Jan. 8 presidential election won by Deni.
"The process was evident of democratic maturity in Puntland," Madeira said in a statement issued in Mogadishu, adding that the AU mission would continue working with Puntland forces to fight violent extremism and terrorism.
"As you begin to deliver on your promises and duties to Puntland and Somalia, as a key partner of Somalia, AMISOM stands ready to support you and your administration in fulfilling your mandate," said Madeira.
Puntland's presidential vote followed similar elections held in South West State on Dec. 19, 2018.
Deni took office as the fifth president of Puntland at Saturday night's inauguration ceremony which was witnessed by Somali President Mohamed Farmajo, senior government officials and representatives of the international community.
Puntland declared itself semi-autonomous in 1998 as fighting raged through most of Somalia.
Since then the region of about 3 million people has had four presidents, all selected by lawmakers who were in turn selected by clan elders.
Madeira also commended Puntland police forces for their role in the implementation of operational readiness assessment of Puntland State Police.
The assessment, he said, was spearheaded by AMISOM and is aimed at gauging the preparedness of the Somali security forces to take over security responsibilities from the AU Mission.
Madeira expressed gratitude to outgoing President Abdiweli Mohamed Ali for his administration's achievements.
"Your administration has achieved a lot for the people of Puntland - we all owe you a debt of gratitude. More importantly, I wish to highlight your statesmanship - this has facilitated a peaceful transfer of power from one administration to another," he said.