Royal Dutch Shell said on Tuesday Shell Canada Limited had recommended a sweetened deal worth C$8.7 billion ($7.4 billion) for the remaining 22% of shares it does not own.
Oil major Shell said it had increased the offer to C$45 in cash for each Shell Canada share, having previously tabled C$40 per share.
Aiming to bolster its own reserves with Shell Canada's Alberta oil sands holdings, the Anglo-Dutch oil firm said in October it aimed to buy out the minority.
Shell Canada, which is also known for its gas station network and Rocky Mountains foothills natural gas exploration, had unanimously agreed to recommend the deal, Shell said.
Investors said last week they were expecting Shell to raise its offer to between C$46 and C$48, with some aiming higher.
Len Racioppo, chief investment officer at Jarislowsky Fraser, which controls 29.5 million shares or 3.6 percent of the Canadian group, said on Friday he believed the value to be in the C$50 a share range, based on years of opportunity in the oil sands.
Shares in Shell Canada closed at C$44.91 on Monday. Shell shares were down 0.3% at 1,713 pence by 0820 GMT.