This study investigates macroeconomic trilemma and Central Bank behavior in Nigeria. The period of investigation spans the quarterly period of 1981–2017. Upon the data stability condition of Zivot-Andrew unit-root test with structural breaks, the Markov Switching Dynamic Regression was employed as the technique of analysis. With a validated trilemma hypothesis, the study found that the trilemma constraints hold for the Nigerian economy but at the expense of the autonomy of the monetary authority. Being the policy variable of the Central Bank of Nigeria, the exchange rate was found to follow two regimes of fixed and managed-float regimes. The results also showed that political risk was found insensitive to the regimes of exchange rate while the foreign sector was considered as a moderating factor for the behavior of the monetary authority; irrespective of the exchange rate regime.JEL Classifications: F41, E32, E52, C22, E58.