"So now the fight of my life begins," she said in a Facebook post this morning.
She said her last smear test was when Rotorua cervical cancer campaigner Talei Morrison, just prior to her passing, rallied her whānau, her friends, the kapa haka community and ultimately NZ to campaign for women - and particularly Māori women - to get their smear tests done regularly.
"Talei's call to wāhine and whānau to get tested was the push I needed to get it done."
Since Allan revealed the battle she faces, fellow politicians, from Labour and other parties, as well as local community members, have been vocal in their support.
Rotorua's Tania Tapsell, the National candidate for the East Coast in last year's election, told the Rotorua Daily Post it was "devastating to see another strong woman battling cervical cancer".
"I have great respect for Kiri Allan and her work and have passed on our love and support to her," Tapsell said.
"This is a huge reminder for women to take on the urgent message from Kiri Allan and my cousin Talei Morrison and 'smear your mea'."
Rotorua's Eruera Keepa, Talei Morrison's brother, knows what it's like to watch a loved one battle cervical cancer.
"Like the rest of the country, we were shocked to read Kiritapu's post this morning," he said.
"It took me back to a time three years ago when Talei was also diagnosed - I had the same sort of gut-drop feeling. You're in a state of numbness, unsure of what to do and where to go.
"Right away, my thoughts and my prayers are with Kiritapu and her whānau as they navigate this journey. Smear Your Mea and Talei's whānau, we're sending all our strength and aroha to them."
He said it was clear that cervical cancer could affect anyone and he encouraged Kiwi women to get health checks and smears.
"I'm drawing from Talei's experience, she was at the height of her career, fitness was at an all-time high and her career aspirations were starting to be realised.
"I see a lot of Talei in Kiritapu. A lot of the experiences and stories shared to us from women with cervical cancer are that because of their lifestyle, the demands of life, going for a regular smear check gets pushed down the priority ladder.
"It's really devastating to hear. Our thoughts and our prayers are with Kiritapu throughout this journey."
Labour MP Tamati Coffey posted on Facebook saying: "In Rotorua we know this story well.
"Cervical cancer is a threat to our women. Te Arawa legend, Talei Morrison fought the good fight raising awareness with women about the benefits of early intervention, before she passed.
"Today it's my colleague Kiri Allan who is about to fight the fight too. We as her work whānau are wrapping around her at this time as she faces one of life's big challenges.
"Mā te Atua koe manaaki e tiaki taku hoa."
Labour MP Jan Tinetti, based in Tauranga, said she was "gutted" when Allan told her about her diagnosis.
"I've been there myself with breast cancer, nothing prepares you for the shock of a cancer diagnosis," she said.
"Now the focus for Kiri is to stay positive and put her and her whānau first - forget about everything else, it can wait.
"She knows she has my utmost support, I'm sendling lots of love to her and her whānau."
Māori Party co-leader and MP for Waiariki Rawiri Waititi also took to Facebook to show his support.
"E te tuahine e Kiri Allan - Labour MP, kāore he kupu. You are so brave! And in the midst of internal turmoil you soldiered on and did the mahi!
"You are still doing it now. He wahine toa koe e te tuahine! I know you will beat this so I'm not going to get sappy with you but thank you for reminding us all how important it is that we encourage our wahine to #SmearYourMea.
"Tāne mā, Wahine mā encourage our wahine to get checked please, drag them to the doctors! Praying for you sister always. Now hurry up and get better so you can get back to stink Pōneke and do what you do best ... tiaki taiao, tiaki te iwi!"