He is still a member of parliament but the constitution bars him from contesting elections unless he gets a pardon or a reprieve from the country's monarch.
Speaking to Reuters on Saturday, Najib challenged his disqualification, saying: "It is subject to interpretation."
"It depends on interpretation in terms of the law, the constitution and whatever happens in court proceedings," Najib said.
Asked if he would contest the next elections due by 2023, he said: "Any politician who would want to play a role would want a seat in parliament."
He declined to specify, however, how he could get around the constitutional barriers.
UMNO, which held power for more than 60 years until outrage over the 1MDB scandal and the opulence displayed by Najib's family helped to dislodge it, is eager to regain public trust under Prime Minister Ismail Sabri Yaakob's nascent government, which must also address factional infighting.
Najib has pursued a public relations campaign to shed his image as an elite and to portray himself as a man of the people. He remains a popular figure on social media, where his critique of past governments has earned him praise.
Najib said in the interview that he has discussed with Ismail Sabri a possible role for him in government. Media reports have said he could be made an economic adviser.
The former premier would not say if he would accept a position, saying his priority was on clearing his name.
He also said UMNO's return to power guarantees "temporary political stability" and that he would not call for early elections, like he had with Ismail Sabri's predecessor Muhyiddin Yassin. Muhyiddin's government collapsed when Najib and some UMNO lawmakers withdrew their support.
Malaysia has seen political instability since the 2018 polls, with two coalitions collapsing because of infighting.
A future Najib candidacy would face a constitutional provision that any person sentenced to imprisonment for more than one year or fined more than 2,000 ringgit ($480) is disqualified from contesting a parliamentary election.
Constitutional lawyer New Sin Yew said Najib can run only if he succeeds in his appeal, receives a royal pardon, or if the king uses his discretion to remove the disqualification despite the conviction remaining in place.
Malaysian and U.S. authorities say more than $4.5 billion was stolen from 1MDB, some of which went into Najib's bank accounts. The U.S. Department of Justice has described the scandal as "kleptocracy at its worst".
Najib, who faces more than 40 charges of abuse of power, money laundering and other offences mostly linked to 1MDB, said he can prove his innocence even as many entities and individuals around the world have admitted guilt or paid hefty penalties and settlements over the scandal.
Malaysian prosecutors have said Najib, who co-founded 1MDB in 2009, played a central role.
Since his election defeat, the United States has returned to Malaysia more than $1 billion in funds it recouped from assets bought with stolen 1MDB money.
Najib said the charges against him were politically motivated and he is pushing for a royal commission of inquiry (RCI) into former Attorney General Tommy Thomas of the post-UMNO government, who first brought the cases against him in 2018.
"I've been insisting on it. The RCI is to establish that it will be a fair and just trial for everyone, not just for me," he said.
Thomas did not respond to an emailed request for comment.
Najib said he had discussed the proposal with Ismail Sabri, who has so far not agreed to it, and he had also discussed it with Muhyiddin, who rejected it.
Spokespersons for Ismail Sabri and Muhyiddin did not immediately respond to requests for comment. ($1 = 4.1700 ringgit)
(Reporting by A. Ananthalakshmi and Rozanna Latiff; Editing by Edmund Klamann) ((email@example.com; Twitter: @AnanthalakshmiA;))