Mark was born on 9th May 1983, the result of a brief relationship between Mike Baldwin and Maggie Dunlop. Maggie lived with Mike but left him when she announced her pregnancy and he tried to convince her to marry him; Maggie didn't think he'd be a suitable father and she hadn't yet decided if she wanted to go through with the pregnancy. But she carried the baby to term and by the time Mark was born Maggie had married Harry Redman, with mother and child taking her husband's name.
Mike first saw Mark when Maggie brought him to Marion Willis's and Eddie Yeats's wedding in October 1983. Maggie offered to let Mike hold Mark but he couldn't bring himself to do so. However, his attitude changed and a few months later after seeing Maggie with Mark in the street, Mike decided he wanted Mark in his life. For a few weeks Mike pestered Maggie to let him see Mark, threatening to take her to court if she kept blanking him. Eventually they came to agreement that Mike would stay out of Mark's life in exchange for an endowment policy Mark would get when he turned eighteen. Mike stayed away and Mark grew up believing Harry was his real father.
When Mark was three, Maggie volunteered Mark for a Hopscotch fashion parade, modelling children's clothes, until she discovered it was run by Mike's wife Susan and pulled him out. Mark first met Mike fleetingly in 1991 when Maggie crossed paths with Mike as his bride Jackie Ingram had ordered flowers from Maggie's shop for their wedding, but Mike's true identity was kept a secret.
In 1992, Mark started at Weatherfield Comprehensive and became friends with Nicky Platt. One of his teachers was Ken Barlow who started dating Maggie; Harry had died some time after June 1991. Mark found it awkward at first but he soon got used to it. Through Nicky, Mark started hanging out in Jim's Cafe, where he was spotted by Mike. Mike decided to drop by Maggie's house and surprise Mark with a Christmas present, but he was shellshocked when Ken answered the door. Ken wasn't happy to discover Maggie's connection to his old enemy Mike but he agreed to keep Mark in the dark, as per Maggie's wishes. Mark was told the truth about who Mike was by Tracy Barlow, who had also told Ken as she thought it was too great a secret to keep hidden. Mark hoped Tracy was lying at first and was so upset that he stayed away from home for hours after finishing school. On returning home in tears, Mark asked Maggie to tell him that Harry was his dad but Maggie, backed into a corner, came clean with him.
When Mike learned the truth had come out, he put pressure on Maggie on let him see Mark. Maggie told Mark it was up to him whether he had a relationship with Mike, and a curious Mark decided to meet him by dropping by MVB Motors. Father and son got off to a good start - Mike made it clear that he did care about Mark even though he stayed away, and Mark was impressed by the way Mike threw his money around, particularly enjoying it when Mike dropped him off at school in his Jag. Mike compared especially favourably to Ken, who took the Redmans on a "boring" holiday to Brittany, resulting in Mark having to pull out of a trip to Euro Disney Mike was planning to take him on. Maggie ended up dumping Ken as he was too obsessed with getting one over on Mike.
In July 1993, when the school year finished, Mike decided Mark should go to a "proper" school and, after considering Eton, decided on Oakhill. He taught Mark the importance of work, getting him and Nicky to wash cars at the garage, and of making contacts, which according to Mike was needed for success. Mark was nervous of the posh pupils at Oakhill and never made any real friends there, but he played for the Under 13s Rugby team and got along well with at least one other boy, Jeremy. Unbeknown to Mark, Mike's finances were stretched to the limit on Mark's school fees and when Mark got excited about a school skiiing trip, he assumed Mike would be able to pay for it, no questions asked. When he overheard Mike and Alma talking about their finances, he told Mike he wasn't interested in the holiday any more.
The following summer, in 1994, Maggie decided to marry Gerry Woodward and move to Felixstowe, taking Mark with her. Mark readily agreed as he didn't enjoy Oakhill, but he still occasionally saw Mike, paying a visit to his new factory in August 1996, with Mike already joking about Mark one day taking over his empire.
In 1999, after leaving school, Mark turned up in Weatherfield to stay with Mike. Mike started him out as a driver for Underworld but he had big plans for his son and heir and in the New Year asked him to be his partner in the business. Making a new start in Weatherfield by renting No.12, over the Kabin, Mark began seeing Leanne Battersby, but Mike disapproved of her as he thought her family was trash. Mark dumped Leanne when she stole £50 from Mike's flat.
The other big change in Mike's life was getting engaged to Linda Sykes, who was much closer to Mark in age than he was. Linda enjoyed teasing Mark but on New Year's Eve he made a pass at her and they had sex on the factory floor, just before Mike walked in. Linda claimed to regret it, threatening to tell the police she was raped if Mark told Mike. Mark had feelings for Linda and on the rebound he dated Clare Machin, an economics student. Linda was jealous of Clare and, when the four went to dinner, Linda kissed Mark in the toilets. They had sex again while Mike was away on business but the guilt of betraying Mike was too much for Mark and he decided to leave Weatherfield. He only stayed when Linda agreed to be friends.
Mike approved of Clare and was disappointed when Mark started going after Leanne again. Mark was impressed when Leanne told him she'd kicked a coke habit and he later finished with Clare. However, he was still confused about his feelings for Linda and when Mike made him start giving Linda driving lessons, they gave into temptation and used the lessons as a cover for sex. Again, Mark was riddled with guilt and wasn't happy when he was cajoled into being Mike's best man when Mike and Linda set a date for their wedding. Linda got Mark to ditch Leanne and they tried to keep things seeming normal but the pressure became too much for Mark and when he met up with his old back-packing friend Craig Brennan, he agreed to go to Amsterdam with him to escape. He asked Linda to go with him but he knew she'd choose Mike for his money and so went without her, leaving a note for Mike telling him his plans. Mike was furious to discover his son had been unable to face him and had a mild heart attack, but Linda played this up and told Mark he had to return home as it might be his last chance to see Mike. Mark returned but he resented Mike for being old and infirm, trapping him in Weatherfield out of duty. However, he then learned from Mike's doctor that Mike had another twenty years in him and that Linda had lied. He went to Amsterdam with Mike's blessing, promising to return for the wedding.
On his return, Mark admitted to Linda that he still wanted her and took her aside at the wedding to beg her to leave with him. Linda refused and the service carried on without Mark, although Mike was humiliated as he had to ask Roy Cropper to stand in as best man. Linda and Mike found a drunk Mark attacking the mini-bar in the bridal suite, and as Mike had a go at Mark for making a fool of him, Mark told him about his and Linda's affair. Mark was sure Linda really wanted him and told Mike he couldn't own people. Mike threw Mark out and had it out with Linda, with them agreeing to make a go of it despite and cut Mark out of their lives. However, their hearts weren't in it and Mike never trusted Linda; they split up a year later.
In September 2001, Mark got a letter from Mike telling him about Alma's death. Before her death, Alma had urged Mike to make reparations with his son. Mark turned up in Weatherfield while Mike was away at Fred Elliott's and Eve Sykes's wedding and decided to turn up and surprise Mike, even though Eve was Linda's mother and Linda would be there. Mike was happy to see Mark, while Linda was rebuffed by him when she tried it on.
By 2006, Mark was living with his girlfriend in Doncaster and was once again estranged from Mike; in the meantime Mike had got closer to his other sons Adam Barlow and Danny Baldwin. He sent Mike a Father's Day card containing his address and was astonished when Mike turned up on his doorstep, out of the blue. Mike was suffering from Alzheimer's disease and was very confused, asking if he could live with Mark. On remembering what had gone on between Mark and Linda, Mike stormed out and went missing. Mark contacted his family in Weatherfield and he was found and taken to hospital there. Mike died of pneumonia a week later. Mark attended the burial but stayed in the background. Afterwards, he visited the factory and met Adam. Adam had been cheated out of his inheritance by Danny, who had used Mike's illness to get him to leave him everything in his will. Mark told Adam that if he were a true Baldwin he'd contest the will.
- While they were at Weatherfield Comprehensive, Mark and Nicky Platt were bullied by Billy Jarvis.
- In 2000, Mark drove a BMW.
- Mark was recurring until 1999 and was played by five actors in total: Thomas Hawkeswood as a baby from 1983 to 1984 (uncredited), Christopher Oakes as a toddler in 1986, Michael Bolstridge as a young boy in 1991, Chris Cook as an adolescent from 1992 to 1996 and Paul Fox from 1999 until the character's final appearance in 2006.
- On his return in 1992, Mark was aged two years by the writers, as they were planning a storyline between Ken Barlow and Mike Baldwin which needed Mark to be the same age as Nicky Platt so that Ken would be his teacher. Chris Cook didn't know of the character's connection to Mike Baldwin until he got the scripts.
- Paul Fox played Mark from 1999 but quit after less than a year in 2000, deciding to pursue other roles.