Bone regeneration has become essential due to various bone diseases, such as bone infections, tumors and resultant bone fracture, birth defects, or bone loss due to trauma or accident. Regeneration of bone is achieved by using a range of materials and scaffolds manufactured through various fabrication techniques. Uses of different materials and scaffold fabrication techniques have been explored over the past 20 years. In this research, polyetheretherketone (PEEK) was used to fabricate highly porous bionanocomposites foams for bone scaffolding. Melt casting and salt porogen (200–500 μm size) leaching methods were adapted to have adequate pore size and the necessary percent of porosity, because pore size plays a vital role in cell implantation and growth. Hydroxyapatite (HA) and carbon particles were used to improve cell attachment to the PEEK foams and to increase the mechanical properties of the materials. Carbon fiber (CF) and carbon nanotubes (CNTs) with various weight percentages (wt %) were uniformly dispersed into the PEEK powder prior to the casting, in order to enhance the mechanical and biological properties and to observe the influence of the carbon particles on the properties of PEEK bionanocomposite foams. Compression testing proved that HA and carbon particles improved the mechanical properties. PEEK foam with 75% porosity and 0.5% CNT concentration showed higher elastic modulus (225.91 MPa) compared to the neat PEEK (66.457 MPa), PEEK + HA (88.827 MPa), and PEKK+ CF (215.05 MPa). Similar observations were seen on the yield stresses of the foam materials. Bone marrow cell growth was observed on PEEK bionanocomposite foams, and a carbon particle showed increased cell attachment over the neat PEEK. The mechanical and biological tests proved that PEEK bionanocomposite foams fabricated via melt-casting and salt porogen leaching have potential use for the bone scaffolding.