The populist, euroskeptic party in Finland's three-party government broke in two Tuesday, days after its election of a new leader threatened to spell the end of the coalition.
Smaller parties such as the Christian Democrats and the Swedish People's Party, and possibly also The Greens, are likely to show interest in entering Sipila's center-right government, which took office in May 2015.
They said they had lost their political home as the party chose hardliner Jussi Halla-aho as the new chairman last Saturday.
Some 20 lawmakers - almost half of The Finns' members in Parliament - left the party and recreated themselves as the New Alternative group.
Sipila was on his way to hand over his resignation to President Sauli Niinisto when the split was announced, making a U-turn rush back.
Tuesday's move will enable Sipila's government to carry on, as it would command 106 seats in the 200-seat Parliament.
"The group [New Alternative] is ready to continue as part of the Sipilä government with the same government programme and constitution", said MP and party chair Simon Elo during a press conference held on Tuesday.
"The new leadership's view of justice, equality, human rights and so on are not the same as the Centre Party's".
"I had expected that one or a few MPs could make that decision (to leave the party), but I could not have anticipated such a big defection", he told reporters.
In 2012, Finland's highest court upheld a conviction and fines against him for inciting ethnic hatred and blasphemy in a 2008 blog post where he criticised Islam and made offensive remarks about Somalis.
"Liberal democracy and a western conception of man must be defended now". Finland has been run by coalition governments with strong majorities for decades.
A member of the European Parliament, Halla-aho has said he would push the two other coalition parties to toughen their immigration policies. The government has sought to improve growth and curb public debt growth by cutting spending and reforming labor laws.