Musharraf, who ruled Pakistan from 1999 to 2008, had lived in exile in Britain and the United Arab Emirates since he had resigned in August 2008, Xinhua reoported.
He launched the All Pakistan Muslim League during exile and will lead the campaign for his party and himself amid serious security threats by the Taliban militants.
On the eve of Musharraf's arrival in Pakistan, the Pakistani Taliban released a fresh video threatening to attack Musharraf for ordering the military in 2007 to raid the Taliban-linked 'Red Mosque' in Islamabad which had killed nearly 90 religious students and 10 security men.
The video showed a group of the militants getting training and a Taliban leader saying that the plan to eliminate Musharraf includes suicide bombers, sniper team, special assault team, and close combat team.
Musharraf played down the threats when he spoke to his few thousands supporters on his arrival at Karachi Sunday. He said he was not worried about the Taliban threats "as they are not new to him".
"Some people had been saying that I would not return. Where are those people?" he asked.
The authorities suspended permission for Musharraf's public meeting at the mausoleum of the founder of Pakistan over security concerns. He instead delivered speech to his supporters at the Karachi airport.
However, he failed to attract a huge crowd presumably because of the threats to his life.
Musharraf said he will take active part in politics and will run for a National Assembly seat in May. He said he will also actively campaign for the other candidates of his party.
The nearly eight-year rule of Musharraf had been marked by controversies. Now that he is back in the country, he will have to face several cases in court, including his failure to prevent the 2007 assassination of former prime minister Benazir Bhutto.
Although he has now restarted his political life, his role is seen as very limited since most his former cabinet ministers have already parted ways with him.
The cases filed against him could also weaken his intention of rejoining active politics.
It is also not clear if he would be allowed to contest elections as he faces several criminal cases including detaining and keeping many judges of top courts who had refused to validate his emergency rule in illegal detention of his critics.
Mushrraf has returned to Pakistan when election process has started and all major parties are busy in the campaign but he will have little time to organise his party and campaign for his candidates.
His policies during 1999-2008, particularly joining the US-led coalition against terrorism and offering the country's air bases to American forces to launch strikes against the Taliban in Afghanistan, were unpopular and he has lost many supporters.
Musharraf will have to struggle to remove his pro-western impression in Pakistan and to convince the people that he has better plans for Pakistan's future than his political rivals.
On Monday, a cleric of the Red Mosque approached the Supreme Court to put Musharraf's name on the Exit Control List alleging that he is the "main suspect" in the military operation against the religious school.
The court had issued arrest warrants for Musharraf during his exile. Now he has got a temporary protective bail but he will face the cases until they are decided.
--IANS (Posted on 26-03-2013)