An adjustable blowout preventer may be configured to be adjustable, such that a central bore of the blowout preventer may be adjusted or repositioned. The blowout preventer may include one or more adjustment mechanisms for adjusting an angle of tilt of the central bore and/or an offset distance of the central bore. The adjustment mechanisms may be arranged between a stack of the blowout preventer and a wellhead. The adjustment mechanisms may generally be tubular structures having angled and/or laterally offset bores therein. The adjustment mechanisms may be configured to be rotatable, such that rotation of the mechanisms may change an angle of tilt and/or lateral offset of the blowout preventer central bore, or portions thereof.