Simoncini started his senior career with Real Rimini in the Italian lower leagues and then spent time with San Marino Calcio.

In 2009 he joined Serie D side Bellaria Igea and made 44 league appearances before joining Cesena for the 2011/12 campaign.

He returned to San Marino in the summer of 2012, joining AC Libertas, where he made almost 120 league appearances and won two domestic cups.

The first choice keeper for San Marino, he moved to Tre Fiori ahead of the 2018/19 campaign.