[2][3] Monroe had a highly successful college career at the University of North Carolina at Chapel Hill from 2000 to 2004.

Nicholas won his first Futures doubles match, partnering Yannis Vlachos to the semifinals of Slovenia F1.

He reached his first final and won his first singles title at the ITF Circuit event in South Africa, when he defeated Stephen Mitchell.

Monroe won his first singles title, South Africa F1 in late October, defeating Stephen Mitchell in the final.

At the beginning of the year, Nick won consecutive doubles titles on the ITF Circuit with partner Sam Warburg in Mexico and Costa Rica.

He partnered with Izak van der Merwe to win the USTA Pro Circuit doubles title in Brownsville, Texas.

In January 2013, Monroe and partner Raven Klaasen made it to the semifinals of the 2013 Aircel Chennai Open, falling to Benoît Paire and Stanislas Wawrinka, after a surprise quarterfinal win over the #1 Seeds Mahesh Bhupathi and Daniel Nestor.

He then teamed up successfully with Simon Stadler to play the Copa Claro in Buenos Aires, Argentina.

Following three semi-final finishes in Chennai, Auckland and Quito all with Artem Sitak, Monroe reached a top 40 doubles ranking of No.

Partnering fellow American Tommy Paul, he also reached at the 2020 French Open the second doubles Grand Slam quarterfinal of his career.

[6] He played his last match on the ATP tour at the 2022 US Open with Keegan Smith as a wildcard pair, where they lost to Fabio Fognini and Simone Bolelli in the second round.

It was announced that he will re-joining the Washington Kastles during the 2020 WTT season set to begin July 12 at The Greenbrier.