Tessa Jowell was promised a "warm embrace of parliamentary love" as she sat in the House of Commons chamber for a debate on cancer treatment.
The motion tabled by Labour's Sarah Jones (Croydon Central) pays tribute to the work of Baroness Jowell in her campaign to help people with brain tumours "live better lives for longer".
Labour former cabinet minister Lady Jowell, who has brain cancer, received a standing ovation in the House of Lords in January after making an emotional plea for more cancer treatments to be made available through the NHS.
Commons Speaker John Bercow said at the start of the debate: "It's my honour, privilege and joy to welcome Baroness Jowell, Tessa Jowell, together with David, together with Matthew, together with Jess and others, to the under gallery in what will be an extremely powerful and I hope constructive debate.
"Can I say to you, Tessa, and I say it on behalf I'm sure of all colleagues, I hope you will feel fortified and inspired by the warm embrace of parliamentary love which you're about to experience."
Lady Jowell took a seat at the back of the Commons chamber in an area usually used by guests of MPs.
Ms Jones worked for Lady Jowell earlier in her career and tweeted a photo of her before the debate, adding: "An absolute pleasure to welcome @TessaJowell back to Westminster ahead of the debate on datasharing and cancer treatment shortly."
Ms Jones will call for greater sharing of health data and more adaptive clinical trials to improve outcomes for brain tumour patients.
The debate follows a landmark summit on brain tumours in London in February, triggered by Lady Jowell's experience following her own diagnosis last year.
Shadow health secretary Jonathan Ashworth paid tribute to Lady Jowell, telling MPs she was an "inspiration".
He said: "Tessa Jowell is an inspiration to all of us and on behalf of the shadow cabinet we pay tribute to her today.
"I hope all members of the House find her bravery extraordinary, she has achieved so much and I just wanted to put on record that we will work constructively with Government to implement many of the recommendations that (Sarah Jones MP) is outlining."