The package, scheduled to be unveiled around 0900 GMT, "should bring progress" for the economy, Widodo said on Twitter on Wednesday.
In March, after the rupiah hit its lowest level since 1998, Widodo launched his first policy package which included a plan to impose temporary anti-dumping import duties and waive visa for dozens of countries.
But the rupiah has weakened steadily since as Southeast Asia's largest economy slowed and the U.S. dollar climbed on expectations the Federal Reserve will raise interst rates later this year, pressuring emerging market currencies.
The rupiah touched a fresh 17-year low on Tuesday and was trading at 14,257 per dollar on Wednesday, taking its losses so far in 2015 to around 19 percent.
The policy package may include measures to attract capital inflows directly and indirectly, Coordinating Minister for Economics Darmin Nasution said.
Nasution has previously said the cabinet was reviewing around 160 regulations seen as hindering investments and may remove or revise some.
The stimulus package also includes tax holidays, changes to financial regulations, and a new beef import policy, he said.
Indonesia's economic growth in the second quarter dropped to 4.67 percent, its slowest since 2009, with prices for commodity and energy exports remaining weak and Widodo unable to push badly needed infrastructure projects past bureaucratic snarls. (Reporting By Gayatri Suroyo, Hidayat Setiaji, Kanupriya Kapoor; Editing by Kim Coghill)