Raised in Australia by his mother and never knowing his father, Tony didn't meet Stefano DiMera until he was a grown man and then spent many years in Europe as Stefano's protégé. Tony came to Salem in 1981 to reconcile with his wife Liz and to check on his assets that were being handled by Stuart Whyland after he noticed that Stuart had made a $25,000 error in the hospital's financial records. After Stuart's illegal actions were uncovered he quickly left town and Tony took over his own finances. Later Tony bought the Twilight Bar and made Trish Clayton-Banning the manager and hired Danny Grant as the bartender. Tony also became infatuated with Renee Dumonde and began wooing her with gifts.
In 1982 Tony kidnapped Liz Chandler, who was still legally his wife since they never divorced. Tony wanted Doug's Place, and with Stefano's help, he forced Liz to spy on Doug for him by threatening to harm Neil Curtis, Liz's new lover, if she didn't. Stefano and Tony had learned that there were titanium deposits underneath Doug's Place and they intended on finding them. They found a passage from a secret room in the DiMera mansion (which Stuart had built) to the basement of Doug's Place, but in the end the entire thing ended up to be a big hoax.
When Liz asked for a divorce, Tony refused and eventually beat and raped her. Later Stefano tried to have Neil killed by planting a bomb in his room. Tony continued to pursue a relationship with Renee, even though her mother Lee warned him to stay away from her. Renee was attacked by the Salem Strangler again and this time she saw his faced, but repressed the memory. Fearing the Strangler would try for a fourth time, Tony DiMera hid Renee in his house.
Later in 1982 Tony proposed to Renee, who accepted. However, Renee discovered Lee's diary and learned that Stefano DiMera was her father, making Tony her half-brother. Renee quickly broke off the engagement, but did not tell him the real reason in order to spare his feelings. Tony refused to let Renee go yet when she told him the truth he refused to believe they were siblings. Tony blamed Stefano for breaking them up, and when Tony tried to leave town, Stefano faked a heart attack. Tony later learned that he and Renee were not related and he had the blood tests to prove it. Unfortunately, Renee had already married David Banning and refused to leave her husband.
Around the same time, Liz Chandler became pregnant with Neil's child, yet Tony believed it was his. He the made his estranged wife a proposition - he would grant Liz her divorce, but only after the baby was born as he wanted to raise the child if it turned out to be his. In 1983 Liz gave birth to a daughter, Noelle, and when Tony realized she was Neil's child, he quickly divorced Liz.
As Tony began to move on with his life, and new love interest Anna Fredericks, Stefano "died" and in his will stated that in order to earn their inheritance Tony and Renee had to live under the same roof for one year and Renee had to stay married to David Banning. The will also declared that the first couple to have a child would receive an extra five million dollars. Anna soon became pregnant with Tony's child causing a jealous Renee to arrange Anna's death in a boating "accident." Unfortunately Tony was on the boat with Anna when the explosion went off. Tony and Anna were rescued by David, but Anna lost the baby. Later that year, Tony learned exactly how Anna got him to marry her - by drugging him! Tony quickly divorced her, even though they had fallen in love by that time.
In 1984 Tony was chained up in his penthouse apartment by his evil look-a-like cousin Andre, who had also assumed Tony's identity. Tony was eventually rescued by Roman Brady, but, after a duel with his imposter, Andre managed to slip away. Andre returned to Stefano's island compound were the two planned on acquiring three prisms designed by Larry Welch's father. Stefano wanted these prisms to heal an inoperable brain tumor he had. One prism was in the belly of an alligator, another in a necklace owned by Daphne DiMera which fell into Calliope Jones' hands and the third in Russia.
After his rescue, Tony, Anna, and Alex Marshall formed a fashion company and picked Haiti for one of their photo shoots. In addition to Tony and Anna, aboard the plane to the shoot were Eugene Bradford, Calliope Jones, Bo Brady, Hope Williams, Liz Chandler, Carlo Forenza, Daphne DiMera and stowaway Andre DiMera! While in flight, Andre shocked his enemies by emerging and demanded the pilot to change courses. Because of his threatening nature, the pilot died of a heart attack and the plane crashed on a remote island. As a result of injuries obtained in the crash Daphne died in Andre's arms. When Tony learned about his mother's fate, he and Andre fought which ended with Andre's demise in a patch of quicksand. Tony gave the necklace with the prism to an island girl, but Stefano managed to get the prism back. Eventually, Roman showed up to rescue his family and friends, but ended up in a fight with Stefano atop a nearby cliff as Bo watched from below. Roman fell and "died" on the beach in Bo's arms. Bo left to get help, but when he returned Roman's body had mysteriously vanished. A short time later the Coast Guard arrived and the survivors were rescued.
Tony and Anna became engaged once again in 1985. Their first marriage attempt was thwarted by Alex who hired an actor to play the part of the minister. Their second try was thwarted when Anna was kidnapped by an Asian potentate. However, their third attempt was successful and Tony and Anna were officially wed. After returning to Salem, Anna was accused of murdering her art dealer, Claud Van Zandt, who had swindled her out of the profits from pieces of hers he had sold. Anna was innocent, but while trying to prove that Tony vanished. Anna was also blamed for her husband's disappearance, but in truth Tony was held captive by a very much alive Claud Van Zandt. Claud was eventually exposed and Anna was let off the hook. Shortly afterwards, Tony was blackmailed by Emma Donovan and was forced to divorce Anna and leave Salem. Anna received divorce papers in the mail, assuming they were from Tony. In reality, Tony had been kidnapped by Stefano and was stranded on a deserted island where he would spend the next twenty-two years of his life.
In 2007, John, Marlena and Anna located Tony and he confirmed what had been stated many years earlier - he was not Stefano's biological child. Although reluctant to face Stefano again, Anna urged him to return to Salem to confront his past (and his "father"). Tony agreed not only to go back with them, but to team up with the Brady Family in order to help end the DiMera/Brady Vendetta once and for all. During this time, Tony also confronted his feelings for Anna and they both admitted they had never truly stopped loving each other and reunited.
Upon returning to Salem, Tony not only faced off with Stefano, but Andre as well who had been impersonating him on and off over the past twenty-two years. After several battles with both of his enemies, Tony came out on top by the time the "Vendetta" ended. With Stefano in a coma and Andre dead, he purchased an advertising agency and started to enjoy his life back in town. His rekindled romance with Anna, however, was a rocky one. She often felt neglected and unappreciated by Tony and he was often frustrated by her hot and cold attitude towards him. Things only got worse when Kate Roberts contracted Tony's new company, DiMera Advertising, to do marketing for her new business endeavor, Kate's Hearth and Home. Tony and Kate working side by side only made Anna more jealous and she and Kate often took verbal jabs at one another. In the end, however, Tony and Anna wed again in May of 2008 and have been enjoying the perks of being married - again!
Tony took the opportunity of being back in Salem to keep an eye on Stefano and bring some respect to the DiMera name by forming a bond with his siblings. He supported Lexie through her struggles with Theo's autism. And, he frequently warned E.J. about getting too involved in Stefano's shady business practices. But when E.J. did not listen to Tony, Tony set off on his own to teach E.J. a lesson.
While E.J. and Philip were fighting over the rights to the alternative fuels project, Tony went directly to Melanie and bought the project for himself. This move angered Philip and he went to confront Tony. Meanwhile, Tony also learned that Nicole lost her baby, faked her pregnancy, and adopted a baby to present as E.J.'s biological child. Thrilled to have two pieces of information that would bring E.J. down, Tony called a family meeting. Tony planned to expose Nicole's secret and the news about the fuels project at once. But, Philip confronted Tony at the pier. They struggled and as Tony was leaving, he tripped and fell over the railing, onto a sharp plank. Nicole was also on the pier and saw the whole thing. Tony was taken to this hospital where he got a chance to leave E.J. a clue (he wrote the letter "B") before he died from a heart attack, which resulted from complications from his fall.