High-level Synthesis is a step used in VLSI design to convert an architecture behavior model, typically coded in C, C++ or SystemC, to a Register transfer language (RTL) model. This step is profoundly used in front end cycle of chip design in VLSI industry. RTL model is essentially a Verilog or VHDL model. Industry uses Synopsys Fusion Compiler (FC) or Synopsys Design Compiler (DC) for HLS. HLS helps implement the architecture’s function in a way which consumes least power, least area and maximizes performance. This chapter circles various HLS methods used in VLSI. The techniques discussed estimate the operation age of an integrated circuit, solve Boolean Satisfiability for computer-aided design problem and summarize methods in integrated circuit reverse engineering with Latency-sensitive HLS for complex DSP Design. Gate sizing with pipelining constraints and geometric programing is also discussed in this chapter. Crosstalk noise mitigation through variable gate bias transmission gate is covered.