Lord Taylor of Blackburn was on a zebra crossing outside the House of Lords when a heavy goods vehicle crashed into him.
The 87-year-old great grandfather who "fought injustice all his life" suffered severe head injuries and died in hospital days later.
Former Nepalese Gurkha Kul Pandey, 56, from Feltham, west London, pleaded guilty to causing his death by careless driving.
He was handed 24 weeks in jail suspended for two years plus 200 hours of unpaid work.
He was also disqualified from driving for three years.
The Old Bailey heard how Pandey was returning to Shepperton after making a delivery when the crash happened at 6pm on November 16 2016.
It was raining and dark as he stopped at the zebra crossing, overshooting the Give Way sign.
He allowed several pedestrians go but pulled out two seconds after Lord Taylor began to cross without checking his mirrors properly.
After hitting the Lancashire peer, he told his assistant in the cab: "I think I have hit someone. I think I have killed them."
In a police interview Pandey, who served for a decade in the Royal Gurhka Rifles, said he found it hard to see the Give Way line at the crossing because it was dark and raining.
Prosecutor Charles Royle said: "Had Pandey stopped at the Give Way line as he should have done, he would be able to see Lord Taylor as he began to cross directly below the windscreen."
Lord Taylor's son Paul Taylor said in a victim impact statement: "My father had been involved in politics for as long as I can remember.
"He absolutely loved being involved in the everyday life in the House of Lords. He really loved to help people and fought injustice all his life."
He divided his time between London and his home in Lancashire and had become even closer to his family since the birth of his two great grandchildren Samuel and Abigail.
He said: "Samuel could not wait for his pops to come back up to Lancashire for the weekends and when the House was in recess.
"Of the two great grandchildren Samuel has taken the death of my father the hardest. He knows he won't be seeing him again."
His great granddaughter says that "since she has some of her pops' genes can she go into the House of Lords", he said.
He went on: "He was not ill and we had only spoke that morning before he went to the Lords.
"I can only describe that feeling like reading a book and someone rips the last few pages out. To say I miss my father is an understatement.
"I do know that as a father, grandfather and great grandfather he will always be missed and his death has had a great impact on his friends and colleagues who still keep in contact with me."
Mitigating, Michael Rawlinson said Pandey was a "proud hard-working man" who put his wife and 15-year-old son first.
He acknowledged the "immeasurable" suffering and hurt of the Taylor family and said Pandey would live with the consequences of his actions every day.
Pandey was born into a poor family in Nepal and had come to Britain in 2010 to give his family a "better life", he said.
Sentencing him at the Old Bailey, Judge Anuja Dhir QC said: "The man you killed was Lord Taylor of Blackburn. He was 87 years old, an active member of the House of Lords and a family man.
"All road users should feel safe but those using a pedestrian crossing ought to feel completely protected because drivers should expect that people will be using them and should take particular care.
"The size of the vehicle you were driving and the weather conditions on that day should have meant that you were even more careful than you would normally be. You were not."
The judge suspended his sentence because of Pandey's "genuine remorse" and the potential effect on his family.
Mr Rawlinson told the court that a "former military man" watching the case in the public gallery had offered to pay any costs on behalf of Pandey.
Following the sentencing, Lord Taylor's family said: "The family of the late Lord Taylor would like to thank the Metropolitan Police for their help, kindness and compassion shown throughout the last 18 months.
"No feelings of hatred or loathing will turn the clock back. We all have to try to move on with our lives."