"We agreed with Tunisia on a comprehensive package of measures that we will now put into practice swiftly,” Ms von der Leyen said after the signing ceremony in Carthage palace.
The preliminary agreement will be published shortly, after being shared with the European Council and Parliament, a representative of the EU commission told The National.
Journalists were not invited to the event where the agreement was signed, but a live stream of the event was provided by the EU Commission and the Tunisian presidency.
The signing ceremony, which was also attended by Italian and Dutch premiers Giorgia Meloni and Mark Rutte, comes as part of the financial assistance package that Ms von der Leyen promised on her visit to Tunis last June.
Ms von der Leyen on Sunday said the partnership would focus on five pillars, which would include strengthening economic and trade ties, personal contact, partnership in sustainable energy and migration.
“An agreement was reached [between EU and Tunisia] in the exchange of money,” a representative for Mr Rutte told Dutch media outlets on Sunday.
Last month, the EU promised Tunisia a €1 billion (about $1.12 billion) support package, about €100 million of which would go towards helping Tunisia to secure its borders.
But the financial aid designated to help Tunisia with its current economic crisis remains pending until certain conditions are fulfilled.
"We will partner to build a resilient Tunisian economy that is more robust to shocks and conducive to growth," Ms von der Leyen said.
"We remain ready to support Tunisia by mobilising macro financial assistance as soon as the necessary conditions are met and as bridging step we are ready to provide immediate budget support."
Tunisia remains unable to secure third-party funding for its struggling public as it has not been able to reach an agreement on a pending $1.9 billion bailout loan from the International Monetary Fund so far.
In the first six months of 2023, about 60,000 migrants crossed the Mediterranean from North Africa, according to the UN International Organisation for Migration, while 2,000 died trying to make the dangerous voyage.
Asked if the deal was mainly about stemming illegal migration – a lightning rod of political controversy in Europe – an EU official told The National that the aid included a range of economic development assistance, such as funding for infrastructure.
But several observers and experts in Tunisia told The National that the migration question is at the centre of these talks and not as peripheral as visiting EU leaders are trying to convey.
"For humanitarian reasons it is vital that we work together to try to stop people making the dangerous and often deadly attempt to reach the EU's shores," Mr Rutte said.
Ms von der Leyen and Mr Rutte said that "it is essential to gain more control over irregular migration", for both partners' sakes.
Sunday's agreement was signed by the European commissioner for neighbourhood and enlargement, Oliver Varhelyi, and a representative of the Tunisian Foreign Ministry.
Watching were Ms von der Leyen, Mr Rutte and Ms Meloni, and Tunisian President Kais Saied.