At 79, Albert will first sign away his rights as the largely ceremonial ruler of the kingdom in the presence of Prime Minister Elio Di Rupo, who holds the political power in this 183-year-old parliamentary democracy.
After the morning ceremony at the royal palace, Philippe, 53, will take the king's oath before the nation's legislators at the parliament building a short walk across the Royal Park in the heart of the city.
Afterward, King Philippe and new Queen Mathilde are expected to greet the crowds below in a balcony scene at the palace before fireworks end a slew of ceremonies marking the day.
Albert announced his abdication plans less than three weeks ago, so there was little time to turn the occasion into a huge international event and no foreign royals were expected at the crowning. Since the royal transition coincides with Belgium's national day celebrations, a military parade had already been planned.
Philippe will face a tough task in the coming months. The fractious nation, ever-more divided by language, holds parliamentary elections in June 2014 amid calls for even more autonomy for the 6 million Dutch-speaking Flemings and 4.5 million French-speakers. The monarchy could find its role even more diminished.
After the last elections in 2010, it took a record 541 days before a government could be formed amid much bickering about how much more power should be sapped from the central state to profit the separate language groups.
Unlike his five predecessors, Albert tried to avoid politics as much as possible and Philippe is expected to do likewise.
Philippe has been groomed for the job as a leader of foreign trade delegations over the past two decades. He and Mathilde have four children.