Philippus proceeded to solve these difficulties demonstrating his political and diplomatic dexterity, his energy and analytical capabilities. The Paionian threat was reduced paying tribute. Archaelaus was assassinated, his brothers survived fleeing to Olynthus. Berisades was given presents and bribes and withdrew his support of Pausanias. Appeasing the Athenians was more complicated. To convince them of his good will, he withdrew from Amphipolis the Macedonian garrison Perdiccas III had brought there without preconditions. He relied on the ability of the city to defend itself, since earlier Athenian attacks had not been successful even without the presence of the garrison. He also offered to renew the earlier alliance between Athens and Amyntas III. The Athenians provided Argaius shipping and a small army contingent for his small mercenary force. He landed in Methone 359 BC and marched to the old capital of Aegae without any further involvement by Athens. The Aegaeans were not prepared to follow him. He had to give up. On his return to Methone his was defeated by Philippus and surrendered with the majority of his army. The Athenians were immediately freed and returned home. Thus any potential conflict with Athens was avoided for the time being.

Having settled the internal affairs, he was now prepared to take care of his neighbours to the north-west. 358 BC he attacked the Paionians who were weekend after the death of their aged king Agis (Αγις). The expedition was successful, large portions of their lands were occupied and the Paionians recognised Philippus's supremacy.

The Illyrians had migrated south under pressure from invading Celtic tribes and had been ravaging the western Macedonian frontier. Perdiccas's campaign against their leader Bardylis (Βάρδυλις) the year before had failed. When Philippus II marched against him 358 BC, Bardylis offered peace but wanted to keep the lands he had conquered. Philippus did not accept and their practically equally strong forces met in the plane of Pelagonia, near present day Monasteri. A bloody battle issued, the Macedonian being victorious at the end. Philippus proceeded to subdue the tribes to the south and finally all the lands east of the lake Lychnitis (Λυχνίτις) accepted his suzerainty. After this success Philippus had a minor involvement in Thessaly and married the Molossian princess Olympias (Ολυμπιάς), the mother of Alexander the Great.

357 BC Philippus II decided that it was a good opportunity to take Amphipolis while the Athenians were engaged in Oeboea and had difficulties with the cities of the Thracian Chersonesus. Amphipolis lay on the crossroads from Macedonia to the Thracian coast and had the harbour Eion at the mouth of the river Strymon. The city was a prerequisite for the expansion of the kingdom to the East. The Amphipolitans asked Athens for help but Philippus offered to hand over the city to them, if they surrendered Pydna at the golf of Thermaïkos. Pydna was an independent member of the Athenian alliance and Athens did not have any right to turn it over. Nevertheless, it accepted and did not help. Amphipolis was taken in the autumn of 357 BC. Late the same year or early 356 BC also Pydna was taken by the Macedonians without any significant resistance from the inhabitants.

360 BC the Thasians had founded their colony Krenides (Κρηνίδες) to the north of their emporium Neapolis (Νεάπολις) close to a gold mine. The city was harassed by the Thracian tribes. Since the Metropolis could not be of help, it asked for support from Philippus II. The Macedonians were willing to oblige. They occupied the city, fortified it, brought new settlers in from the kingdom and renamed it Philippi (Φίλιπποι). It was not incorporated into the kingdom immediately and issued its own coins until 344 BC. Philippus II used also the opportunity to occupy the region of Pangaeum (Παγγαίον) the mines of which provided a yearly income of 1000 talanta.

After the death of the Thracian king Cotys I (Κότυς Α', 384-359 BC) the Odrysian Kingdom was partitioned among Amadocus II (Αμάτοκος Β', 359-351 BC) to the east, Cersobleptes (Κερσοβλέπτης, 359-341 BC) in a central part and Berisades (Βηρίσαδης, 358-356 BC) to the west. The latter was succeeded by his son Cetriporis (Κετρίπορις, 356-351 BC). The establishment of Philippi threatened the possessions of the latter. He arranged an alliance among himself, the Paionians, the Illyrians and Athens to regain Krenides by any means. The Macedonians defeated the former three members of the alliance individually before the Athenian Ekklesia had even been notified and agreed to the alliance. 

After these successful military and diplomatic campaigns and the birth of Alexander the Great 356 BC the Macedonians demanded from Philippus to access the throne, which he did. Amyntas was not formally removed and stayed at his court. The Macedonian influence extended form lake Lychnitis in the west to the Nestos river in the east including western parts of the Odrysian Kingdom, from Paionia to the north to Chalcidice and Thessaly to the south.