The operator is backing the launch with one million free kids' places across 16 countries and island destinations in Europe and the Caribbean.
However, it has warned the available free kids' places on holidays to Mexico, Jamaica and the Dominican Republic will only be available on bookings made by 16 November.
Other destinations with free kids' places include the Balearics, the Canaries, Greece, Turkey and Florida.
Tui says "families able to save on selected breaks when booking early", adding free kids' places across the other 13 destinations featuring in the programme will be available "while they last".
"The earlier families book, the more choice they'll have," said Tui. Free kids's places cover children's flights, accommodation and transfers, as well as their food and drink where families are travelling all-inclusive.
In total, the programme features 2,200 hotels across 70 destinations; besides its family-focused brands like Holiday Villages and SplashWorld hotels, there are Tui Blue and Sensatori options available for adults.
Tui has also put its largest-ever weddings programme on sale for summer 2028, which spans 230 venues across 21 destinations, including Portugal and Malta – and for the first time, Zanzibar.
Chris Logan, Tui UK and Ireland Commercial Director, said the launch offered families "a brilliant opportunity to get ahead and make their holiday budget go further".
He reiterated Tui's messaging: "Booking early gives customers the widest choice of hotels, departure airports and travel dates, especially in the busy school holidays."
Free kids' places are available on new bookings, with one place available for every two full-paying adults in a qualifying room, apartment or villa.
The 16 countries and island destinations comprising Tui's summer 2028 programme are: the Balearics, the Canaries, Greece, Cyprus, Croatia, Egypt, Morocco, Tunisia, Turkey, Italy, Bulgaria, mainland Spain, Florida, Mexico, the Dominican Republic and Jamaica.
