The remarkable flexibility, stable chemical structure, and extraordinary thermal, electrical, and optical properties of carbon nanotubes (CNTs) are promising for a variety of applications in flexible and/or high-temperature electronics, optoelectronics, and thermoelectrics, including wearables, refractory photonics, and waste heat harvesting. However, the long-standing goal in the preparation of CNT ensembles is how to maintain the extraordinary properties of individual CNTs on a macroscopic scale. The polydispersity and randomness remain two main challenges. Here, we will discuss different methods for creating macroscopically aligned CNTs, including spontaneous formation of wafer-scale aligned CNT films via controlled vacuum filtration and production of ultrahigh-conductivity CNT fibers and films through solution spinning and coating. We will then describe the optical, dc and ac electrical, thermal, and thermoelectric properties of these materials. These results are promising for device applications in various fields such as flexible CNT broadband detectors, spectrally selective thermal emitters, and thermoelectric devices.