More than 2,000 former Gurkha soldiers have been refused permission to settle in the UK because they retired before July 1997.
According to the Daily Star, Lumley will be in the gallery of the House of Lords this afternoon with Justice campaign co-ordinator Peter Carroll to see the third reading of a bill, which would see a change in the law.
She will then meet soldiers and supportive MPs.
Lumley, whose own father served with the Gurkhas for 30 years, said: "I will be in Portcullis House asking for MPs on all sides of the House to support this bill and our Gurkha heroes.
"The fact that the bill has enjoyed cross Party support in the Lords is a magnificent and hopeful sign. The Government has a historic opportunity to put right this terrible wrong. Letting this bill stand will honour our debt."
A similar bill has been introduced in the House of Commons by Bob Russell, Liberal Democrat MP for Colchester.
Campaigners are hoping to garner a million signatures for their petition and persuade the Government to pass the new laws.