RNA - The suspect, Joseph Michael Schreiber, 32, was arrested on Wednesday while walking along a sidewalk in Fort Pierce, according to the St. Lucie County Sheriff's Office.
Monday's arson attack is being prosecuted as a hate crime under Florida law. Schreiber faces at least 30 years in prison if convicted.
No one was inside the building at the time, but the blaze forced the congregation to hold prayer services elsewhere.
As a "habitual felony offender" whose criminal record includes armed robbery, Schreiber also would be eligible for life in prison, police said.
The blaze heavily damaged the Islamic Center of Fort Pierce, a place of worship for gunman Omar Mateen before he shot 49 people to death at a bar in June.
The nightclub shooting, which also wounded 53 people, was the deadliest mass shooting in modern US history.
The Fort Pierce Islamic Center has reported numerous threats of violence and intimidation since it was identified publicly as Mateen's place of worship.
An examination of Schreiber's social media account also revealed "multiple anti-Islamic posts and comments," Sheriff's Major David Thompson said.
A Facebook page apparently belonging to the suspect include a message that said, "ALL ISLAM IS RADICAL, and should be considered TERRORIST AND CRIMANALS," written in capital letters.
The nightclub shooting unleashed a wave of anti-Muslim propaganda in the US. After the incident, Republican presidential candidate Donald Trump said the US was being threatened by what he called radical Islam.
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