Ardern is expected to continue lobbying the Australian Government to improve the rights of New Zealanders living in Australia, possibly through reopening pathways for kiwis to get Australian citizenship more easily, or by making it harder for Australia to deport New Zealand citizens with criminal convictions, who have lived in Australia for most their lives.
Australia Prime Minister Anthony Albanese will be considering New Zealand's position, having been in the job for little more than a month.
In this time, he has had ample face time with Ardern, meeting in both Sydney and Europe. The leaders of their respective countries' labour parties have portrayed their relationship as particularly warm and family-like.
Albanese last month tempered expectations, saying the "501 policy" around deportations wouldn't be completely scrapped.
But, drawing attention to "some of the [individual] cases" – an apparent allusion to some of the extreme deportations of people with no ties to New Zealand – he said he wanted to take a "common-sense" approach.
Ardern and Albanese will have their formal "leaders' meeting" on Friday.
The engagement will also give them an opportunity to debrief following their trip to Europe.
Speaking as guests at a Nato summit, both leaders raised concerns over (in Ardern's words) a "more assertive" China in the Pacific. China responded critically to both New Zealand and Australia.
Australia has in recent years taken a harder line approach towards China than New Zealand. China has responded by curtailing some of its exports.
Ardern is expected to continue walking a tightrope on the geopolitical front, stressing (as she did at the Nato summit) that New Zealand has a "fiercely held independent foreign policy".
Her discussions with Albanese over China will set the scene ahead of the Pacific Islands Forum in mid-July, where matters around China's increasing presence in the Pacific will be thrashed out among the region's leaders.
Russia's invasion of Ukraine and climate change will also be hot topics of discussion during the week, as will economic issues around inflation, tightening monetary conditions, strained labour markets and disrupted supply chains.
Ardern and Albanese will both also speak at the Australia-New Zealand Leadership Forum in Sydney, which will be attended by ministers Damien O'Connor (trade and export growth), Stuart Nash (tourism and small business), Willie Jackson (Māori development), Michael Wood (immigration), Ayesha Verrall (Covid-19 response), James Shaw (climate change) and Grant Robertson (finance) – provided he has recovered from Covid-19.
There will be plenty of photo opportunities, with Ardern and Albanese also addressing a Trans-Tasman Innovation and Growth Awards event.
New Zealand's position on foreign policy will be scrutinised by Australia, when Ardern gives a speech at an event organised by the Lowy Institute – an international policy think tank.
As for the business leaders on the trip, they will be hoping the New Zealand Government helps open doors for them to further penetrate the Australian market, which is often their first step to markets further afield.
Companies represented on the trip range in size and speciality, from food and beverage to consumer goods, technology, venture capital, manufacturing and tourism.
They include Xero, Beca, Warren and Mahoney, Sharesies, Banqer, Yu Mei, Kow Tow, Garage Project, Kia Ora Honey, Healthpoint, The Mindlab, OKU Herbal Teas, and Tourism Industry Aotearoa, among others.
In Melbourne, Ardern will attend an ANZ business breakfast event and a dinner showcasing New Zealand food and beverage.
In Sydney, she will engage with tourism leaders from both countries. Australia is New Zealand's largest source of visitors. Over 1.55 million people visited New Zealand from Australia in 2019, contributing an estimated $2.7 billion to the economy.
Ardern will also meet with key Australian investors, launch the New Zealand "Discover New" collaboration with department store, David Jones, and attend a dinner showcasing New Zealand high-end retail brands and featuring New Zealand food and beverage products.
Business and political leaders will use the trip as an opportunity to rekindle existing relationships and build new ones – including with Australia's new centre-left government.
They will be looking to leverage New Zealand and Australia's shared values, despite some divergence in foreign policy in recent years.
Businesses and government will play the long game, rather than use the trip as an opportunity to secure quick wins.
With geopolitical tensions rife in not only Europe, but the Pacific, and regionalisation becoming more prominent as war undermines globalisation, New Zealand's relationship with old mate, Australia, is particularly important.
Now, more so than in some time, there is a lot to gain from strengthening the relationship rather than taking it for granted.
The question will be, to what extent will this companionship extend to kiwis in Australia seeking better treatment?
