Two years in the planning, the force brings together troops from Burkina Faso, Chad, Mali, Mauritania and Niger in a desert region the size of Europe.
Former colonial power France is currently leading counterterrorism operations there through its 4,000-strong Barkhane force, but is keen to share the burden as its military is engaged on various fronts.
The ambitious goal is to have 5,000 local troops operational by mid-2018, wresting back border areas from extremists including a local Al-Qaeda affiliate.
But Macron -- who has had a busy week of diplomacy after a climate summit on Tuesday -- has expressed frustration at delays, with the first mission only taking place last month in the volatile border zone between Burkina Faso, Mali and Niger.
"It's an initiative that's getting more powerful, but speed is a problem," French Defense Minister Florence Parly told RFI radio.
"We have to go faster," she said. "The objective is to be able to move forward faster on financing and the military structure."
The five Sahel countries are among the poorest in the world, and funding will be high on the agenda as their presidents join Macron in Celle-Saint-Cloud outside Paris.
Officials from oil-rich Saudi Arabia -- which may confirm a $100 million (85 million euro) contribution, according to the French presidency -- are notably on the guest list.
UAE officials are also attending along with the Italian and Belgian prime ministers as well as representatives of the European Union, African Union and United States.
Priority number one is to re-establish law and order in the border zone where several hundred soldiers, backed by French troops, carried out last month's debut mission.
Militants have mounted repeated attacks in recent months, including an assault in Niger on October 4 which killed four US soldiers and another two weeks later in which 21 Niger troops died.
In August, gunmen stormed a restaurant in Burkina Faso's capital Ouagadougou, killing 19 including foreigners.
The G5 force is set to work alongside Barkhane troops and the UN's 12,000-strong MINUSMA peacekeeping operation in Mali -- the most dangerous in the world, having lost 90 lives since 2013.
The arid Sahel region has become a magnet for Daesh since Libya descended into chaos in 2011.
In 2012, Al-Qaeda-affiliated terrorists overran the north of neighboring Mali, including the fabled desert city of Timbuktu.
France intervened in 2013 to drive the extremists back but swathes of central and northern Mali remain wracked by violence, which has spilled across its borders.