Saint John police announced the arrest Tuesday evening. Oland will appear in court Wednesday, Sgt. Jay Henderson said in a media release.
Police will hold a press conference Wednesday at 10 a.m..
Police have previously said they consider Dennis, 45, the prime suspect, and police Chief Bill Reid had repeatedly said he expected an arrest in the case before the end of the year.
Family stands by Dennis Oland
Derek Oland, brother of Richard, said the family believes the police have got it wrong.
"This situation truly is a tragedy for all of us who are part of the Oland family, and we are striving to understand and deal with the many implications," he said in a media release.
"We will rely on the court of law, believing in the judicial process. We believe our nephew and cousin Dennis is, in fact, innocent and we will support him and his family members through the course of whatever legal actions unfold."
Dennis's lawyer, Gary Miller, was seen entering the Saint John police headquarters on Tuesday shortly before 7 p.m. He declined to comment.
Bill Teed, who is representing other members of the Oland family, also declined to comment.
A jacket seized from Dennis's bedroom closet had blood on it that matched his father’s DNA profile, recently released documents related to the investigation revealed.
The brown Hugo Boss sports jacket had a dry-cleaning tag attached that appears to correspond to a seized dry-cleaning receipt dated July 8, 2011.
Oland owed father more than $500,000
Previously released documents show police believe Dennis, who was the last known person to see his father alive, lied to them about what clothes he was wearing that day, based on video surveillance of him and statements from two witnesses.
The documents indicate a possible financial motive.
Dennis, a stockbroker and investment adviser, owed his dad more than $500,000, and the documents suggest he fell behind in making payments in the months leading up to his father’s death.
No details about how Oland died have been released. Those details are considered so-called hallmark evidence that only the killer or killers would know. No charges have been laid in the homicide.
Police spent several hours executing a search warrant at Dennis's Rothesay home on Gondola Point Road on July 14, 2011, one week after his father's body was discovered.
Officers seized a total of 57 items, including legal papers, clothing, the lint trap of the dryer, and garbage bags and their contents.