diff --git a/addons/project/static/tests/tours/project_sharing_tour.js b/addons/project/static/tests/tours/project_sharing_tour.js
index e74ef58c870..2cf1ed3aafa 100644
--- a/addons/project/static/tests/tours/project_sharing_tour.js
+++ b/addons/project/static/tests/tours/project_sharing_tour.js
@@ -21,7 +21,7 @@ const projectSharingSteps = [...stepUtils.goToAppSteps("project.menu_main_pm", '
     trigger: '.ui-autocomplete a.dropdown-item:contains("Georges")',
     in_modal: false,
 }, {
-    trigger: 'footer > button[name="action_send_mail"]',
+    trigger: 'footer > button[name="action_share_record"]',
     content: 'Confirm the project sharing with this portal user.',
 }, {
     trigger: '.o_web_client',
diff --git a/addons/project/wizard/project_share_wizard.py b/addons/project/wizard/project_share_wizard.py
index 80ec5c9e053..1efed798eaf 100644
--- a/addons/project/wizard/project_share_wizard.py
+++ b/addons/project/wizard/project_share_wizard.py
@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
-from odoo import api, fields, models
+from odoo import api, fields, models, _
 
 
 class ProjectShareWizard(models.TransientModel):
@@ -43,13 +43,30 @@ class ProjectShareWizard(models.TransientModel):
             else:
                 wizard.resource_ref = None
 
-    def action_send_mail(self):
+    def action_share_record(self):
+        # Confirmation dialog is only opened if new portal user(s) need to be created in a 'on invitation' website
         self.ensure_one()
+        on_invite = self.env['res.users']._get_signup_invitation_scope() == 'b2b'
+        new_portal_user = self.partner_ids.filtered(lambda p: not p.user_ids) and on_invite
+        if not new_portal_user:
+            return self.action_send_mail()
+        return {
+            'name': _('Confirmation'),
+            'type': 'ir.actions.act_window',
+            'view_mode': 'form',
+            'views': [(self.env.ref('project.project_share_wizard_confirm_form').id, 'form')],
+            'res_model': 'project.share.wizard',
+            'res_id': self.id,
+            'target': 'new',
+            'context': self.env.context,
+        }
+
+    def action_send_mail(self):
         if self.access_mode == 'edit':
             portal_partners = self.partner_ids.filtered('user_ids')
             self.resource_ref._add_collaborators(self.partner_ids)
             self._send_public_link(portal_partners)
-            self._send_signup_link(partners=self.partner_ids - portal_partners)
+            self._send_signup_link(partners=self.with_context({'signup_valid': True}).partner_ids - portal_partners)
             self.resource_ref.message_subscribe(partner_ids=self.partner_ids.ids)
             return {'type': 'ir.actions.act_window_close'}
         return super().action_send_mail()
diff --git a/addons/project/wizard/project_share_wizard_views.xml b/addons/project/wizard/project_share_wizard_views.xml
index 512dba38029..f42284c4e4f 100644
--- a/addons/project/wizard/project_share_wizard_views.xml
+++ b/addons/project/wizard/project_share_wizard_views.xml
@@ -21,7 +21,23 @@
                 </group>
                 <field name="note" placeholder="Add a note" nolabel="1"/>
                 <footer>
-                    <button string="Send" name="action_send_mail" attrs="{'invisible': [('access_warning', '!=', '')]}" type="object" class="btn-primary" data-hotkey="q"/>
+                    <button string="Send" name="action_share_record" attrs="{'invisible': [('access_warning', '!=', '')]}" type="object" class="btn-primary" data-hotkey="q"/>
+                    <button string="Discard" class="btn-secondary" special="cancel" data-hotkey="x" />
+                </footer>
+            </form>
+        </field>
+    </record>
+
+    <record id="project_share_wizard_confirm_form" model="ir.ui.view">
+        <field name="name">project.share.wizard.view.form</field>
+        <field name="model">project.share.wizard</field>
+        <field name="arch" type="xml">
+            <form string="Confirmation">
+                <p>People invited to collaborate on the project will have portal access rights.</p>
+                <p>They can edit shared project tasks and view specific documents in read-only mode on your website. This includes leads/opportunities, quotations/sales orders, purchase orders, invoices and bills, timesheets, and tickets.</p>
+                <p>You have full control and can revoke portal access anytime. Are you ready to proceed?</p>
+                <footer>
+                    <button string="Grant Portal Access" name="action_send_mail" type="object" class="btn-primary" data-hotkey="q"/>
                     <button string="Discard" class="btn-secondary" special="cancel" data-hotkey="x" />
                 </footer>
             </form>