Thanking locals for their help in search efforts, Ms Quoirin said: "You have given up your time especially at a special festival time", referring to Hari Raya Haji, the Islamic "festival of sacrifice" celebrations.
Announcing the reward, Nora's family said their daughter is "so precious to us" and said their "hearts are breaking".
"We will continue the search for Nora".
"We see you working so hard and also praying with us and being with us".
Police are treating it as a missing persons case but Nora's family believe she may have been abducted.
"If you have any information at all, please call the police hotline here on 01112285058 or email email@example.com from outside Malaysia".
British police arrived in Malaysia earlier today to join forces with their Irish and French counterparts as the search for Nora entered its ninth day.
Anyone with information is asked to contact the Lucie Blackman Trust intelligence on opslbtrust.org or +44 800 098 8485.
Quoirin's family arrived August 3 for a two-week stay at the Dusun, a small resort located in a durian orchard next to a forest reserve 63 kilometers south of Kuala Lumpur.
A police forensic team is still analysing fingerprints found in the cottage where the girl went missing.
The Lucie Blackman Trust, a charity supporting missing people overseas, said police believed the teenager could have been taken.
After initially dismissing abduction and foul play as the reason, the police finally said last week it is also probing abduction.
In an emotional statement, Nora's mother Meabh said: "Nora is our first child".
"We are especially anxious because Nora has learning and developmental disabilities, and is not like other 15-year-olds".
"She never goes anywhere by herself. We don't know how long she can survive".
The search has now expanded to include the slopes of a nearby mountain, said Che Zakaria Othman, deputy police chief of Negeri Sembilan state.
Nora has been missing for more than a week.
Nora and her mother and father, who are Irish and french respectively, arrived in Malaysia from the United Kingdom - where they have been living for 20 years - on Saturday, August 3.
Nora's mother thanked the searchers.
They said in a statement: "Nora is not like other teenagers".
Khalid Mohamad said he believed the youngster was lured away from the eco-resort in Malaysia by a "genie" - because of her special needs and had chosen her as its stepchild. "Most important now, the child will be released", he said in the video. She is unable to do maths and so things like money are impossible to manage.
A number of Sharmans are involved in the search effort.
Nora Anne Quoirin, 15 and with learning disabilities, was reported missing on August 4 after her family arrived at the Dusun resort in Seremban, about 70 km (44 miles) south of Malaysia's capital Kuala Lumpur. We are so grateful for everything that you are doing for us, everyone who is helping here and not from here.
"We are committed to finding her", he told reporters.
"And thank you so much".