However it was not that way for so many, and Robertson spoke of a friend, James, who was met with "anger, rejection and derision", and ultimately took his own life.
"To James and the many like him from all parts of rainbow community ... this legislation is for you," Robertson said.
"We cannot bring you back, we cannot undo all the hurt, but we can make sure for the generations to come we provide the support and love you did not get and protect you from the harm of those who seek to try to stop you from being who you are.
"We will never forget you."
Robertson said he acknowledged for some the bill did not go far enough in terms of penalties, but "got the balance right".
For those opposing the bill, Robertson said the intent was to deter such practices, and did not undermine freedom of speech or worship. It would apply "only when the particular practice intends to change or suppress".
Fellow Labour MP and Minister of Conservation Kiri Allan this evening revealed she went through conversion therapy at 16 through her church.
"I desperately tried to 'pray the gay' away - to be accepted by my family, community and church," she said in a tweet.
"My 'illness' and 'weakness' to temptation was etched as sin into my skin.
"It took a long time to shake that shame and trauma. Tonight our Parliament will ensure this practice is banned in our country for good.
"For our next generation of babies, I am so incredibly relieved. Thank you to everyone that championed this change."
Green MP and rainbow spokeswoman Dr Elizabeth Kerekere said the bill was not the "be all end all", particularly for trans, intersex and non-binary people who the party would keep fighting for.
National justice spokesman Paul Goldsmith and MP Joseph Mooney, and Act deputy leader Brooke Van Velden also spoke in support of the bill.
The bill passed its second reading last week, with all but seven MPs in support. Michael Woodhouse, Louise Upston, Shane Reti, Simon O'Connor, Melissa Lee, Simeon Brown and Simon Bridges voted against the bill then.
The first reading of the bill passed in August.
The bill, which will come into effect in six months, creates two new criminal offences for either the most serious cases of harm or where there is heightened risk of harm. The bill also creates a pathway for civil redress.
Under the bill, it will be an offence to perform conversion practices on a child or young person aged under 18, or on someone with impaired decision-making capacity. Such offences would be subject to up to three years' imprisonment, and up to five years where it has caused serious harm, irrespective of age.
The Attorney-General needs to give consent for those prosecutions.
The bill also provides for civil redress, with complaints able to be made to the Human Rights Commission and the Human Rights Review Tribunal.
Chief Human Rights Commissioner Paul Hunt said they were establishing a conversion practices response services team.
"This legislation sends an unequivocal message that conversion practices, which have destructive and sometimes fatal consequences, have no place in this country."
Labour promised ahead of the 2020 election to ban conversion practices, and a petition Kerekere launched in February 2021 accumulated 157,764 signatures in a matter of days.
The bill itself received nearly 107,000 public submissions.
