Nanotechnology is providing a new set of tools to the engineering community to design nanoscale components with unprecedented functionalities. The integration of several nano-components into a single entity will enable the development of advanced nanomachines. Nanonetworks, i.e., networks of nanomachines, will enable a plethora of applications in the biomedical, environmental, industrial and military fields. To date, it is still not clear how nanomachines will communicate. The miniaturization of a classical antenna to meet the size requirements of nanomachines would impose the use of very high radiation frequencies. The available transmission bandwidth increases with the antenna resonant frequency, but so does the propagation loss. Due to the expectedly very limited power of nanomachines, the feasibility of nanonetworks would be compromised if this approach were followed. Therefore, a new wireless technology is needed to enable this paradigm. The objective of this thesis is to establish the foundations of graphene-enabled electromagnetic communication in nanonetworks. First, novel graphene-based plasmonic nano-antennas are proposed, modeled and analyzed. The obtained results point to the Terahertz Band (0.1-10 THz) as the frequency range of operation of novel nano-antennas. For this, the second contribution in this thesis is the development of a novel channel model for Terahertz Band communication. In addition, the channel capacity of the Terahertz Band is numerically investigated to highlight the potential of this still-unregulated frequency band. Third, a novel modulation based on the transmission of femtosecond-long pulses is proposed and its performance is analyzed.% in terms of achievable information rates. Fourth, the use of low-weight codes to prevent channel errors in nanonetworks is proposed and investigated. Fifth, a novel symbol detection scheme at the receiver is developed to support the proposed modulation scheme. Sixth, a new energy model for self-powered nanomachines with piezoelectric nano-generators is developed. Moreover, a new Medium Access Control protocol tailored to the Terahertz Band is developed. Finally, a one-to-one nano-link is emulated to validate the proposed solutions.