In 1975, Oldfield collaborated on albums with other musicians associated with him, such as David Bedford, Edgar Broughton, and Tom Newman, while the impact of Tubular Bells continued in crescendo. That year, Oldfield was awarded a Grammy Award for Best Instrumental Composition.

Around that time, Oldfield released "Portsmouth", another traditional song that reached number three, one spot above "In Dulci Jubilo". Between 1976 and 1978, due to long-standing psychological problems, Oldfield secluded himself in his home in Gloucestershire. There he began the work that would culminate in the release of Incantations. During this hiatus, Virgin released the quadruple album Boxed, a collector's set containing his three albums released up to that point and a fourth disc with singles, special collaborations on other artists' albums, and a rare track sung by Mike himself and David Bedford called "Speak (Tho' You Only Say Farewell)".

In January 1977, Mike made his first stage appearance in two and a half years, as a guest guitarist in a live performance of David Bedford's suite The Odyssey, based on Homer's work. This was followed by the almost simultaneous release of two singles: one was a version of Rossini's "The William Tell Overture", and the other "Cuckoo Song", another arrangement of a traditional English folk song, though neither achieved significant success.

Following a live performance of Ommadawn, Oldfield's fourth album, Incantations, was released in late 1978. In the years after Ommadawn, symphonic rock and its grandiosity had lost global appeal due to the rise of punk music, which was far more accessible to a youth demanding idols who matched their own personal capabilities and had nothing to do with the supergroups of musical geniuses like Pink Floyd or Genesis. Within his own country, punk had a negative impact on Oldfield. When asked what he thought of the trend, he replied, "Punk rock? I've never heard of it". Perhaps because of all this, Incantations felt somewhat out of place. It was Oldfield's first double LP, consisting of four suites with different movements, again drawing on Celtic and ethnic sounds combined with a legendary atmosphere, heightened by lengthy ritual chants.

The change in atmosphere compared to his other works—this one much more complex, hypnotic, and rhythmic, influenced in part by the world music and minimalism movement being explored by composers such as Philip Glass, Terry Riley, Wim Mertens, Michael Nyman, and Vangelis—meant it was less successful than its predecessors. It reached number 14 on the British charts and remained in the UK Top 20 for a time.

Around that time, Oldfield gave numerous interviews to promote the album and discuss his radical personality change, brought about mainly by his attendance at seminars based on exegesis, a controversial therapy created to improve self-confidence. Thanks to exegesis, he believed he had discovered the more positive side of his character. In an interview from that period, he literally said that he had experienced what he could describe as a "rebirth," helping him to delve deeper into himself and human nature. The cover image, taken by Trevor Key, features Oldfield at Cala Pregonda, a beach in Menorca. It was here in Menorca that Oldfield would establish his permanent residence in later years.

In March 1979, he released the single "Guilty", whose sound closely resembled that of the popular music of the time. Some journalists detected a certain disco style in this track, recorded with studio musicians in New York. Although he was already an undisputed master of studio recordings, live concerts had also been an important part of Oldfield's artistic life from the beginning. After undergoing therapy in the late 1970s, he felt ready to tour with a large group of musicians; this resulted in the Exposed tour, also known as the Tubular Shows. Mike Oldfield's first international tour took place in 1979, almost six years after the release of Tubular Bells. The expensive show featured a 50-piece orchestra and choir, including members of the Queen's College Girls Choir. It was accompanied by a 25-person entourage of roadies and technicians, and three trailers to transport all the equipment. Filmmaker Ian Eames created three films that were projected in the background during the concerts.

The tour began in Spain and then continued through Belgium, France, the Netherlands, and Germany. In August, Virgin released Exposed, a double live album recorded during the tour. In the following years, Mike revealed that the venture was a financial disaster, leaving him with a million pounds in debt, which he partially covered with the release of the tour album and paid off with the accelerated release of Platinum.

Platinum broke with the pattern of his first four albums, structured as long tracks without clear divisions between their movements. Its composition was divided into four segments, followed by short instrumental pieces, with a certain experimental and playful spirit. Among the songs on Platinum, "Punkadiddle" stood out, with which Oldfield intended to ridicule the punk movement.

As a Christmas single, Oldfield released "Blue Peter", an adaptation of a traditional song, used in this case as the theme song for a children's program of the same name. The single reached number 19 on the UK charts. Royalties were donated to the Cambodia relief campaign launched by that children's program.

In the spring of 1980, Oldfield formed an eleven-piece band for another 40-day tour of Europe, with a show featuring songs from Platinum. These live performances culminated in a show before 43,000 people at the Knebworth Fairy Park Festival on June 21, 1980. After arriving by helicopter, he played after The Beach Boys, Lindisfarne, and Santana. A journalist from the Record Mirror praised Oldfield's excellent performance, highlighting his "crystal-clear sound."