Honorary Mining Counsellor Juuso Walden's era at the head of United ended at the close of the 1960s. Jämsänkoski Superintendent Lauri Tiilikka retired, and was succeeded by the former Deputy Superintendent, Olof Palmgren. The 1970s fulfilled the expectations set for Kaipola mill, and Jämsänkoski acquired a fine grade papermaking machine, PK 4. The processing section was given new premises on the Myllymäki industrial estate. The Pekilo plant, using waste liquor from the pulp mill as raw material, was completed in 1976.

The reforms implemented in the time of CEO Niilo Hakkarainen turned the company round and back into profit. Among other measures, United abandoned its agriculture section, and many functions were centralised. Production was reduced and staffing cuts made. The centralised management was disbanded and more power and responsibility given to individual plants.

The thermomechanical pulp developed at Kaipola in the 1970s proved to be an excellent raw material of paper. Operation of the Jämsänkoski chemical pulp mill ended in 1981. Paper manufacture was concentrated on types for which thermomechanical pulp could be used as main raw material. As the result of JÄPRO, the Jämsänkoski project, a thermomechanical pulp mill was constructed and PK 5 obtained. In the mid-1980s the mills' power supply was updated to use mainly peat. The decade brought good results for United; paper was selling at a good price. The most successful was Kaipola mill, which acquired another two papermaking machines at the end of the decade.

In international terms, Finnish forest companies were small. From the mid-1980s, the forest industry strategy was to merge into larger units. Forest industry investments grew towards the end of the decade, and the industry was running at full capacity. The year 1988 was even called 'the crazy year'. In the same year, the Jämsänkoski mills celebrated their centenary year.

United Paper Mills Ltd had achieved good results, and it was decided that less successful forest companies should be merged with it. United bought out Joutseno-Pulp in 1988. The following year, Kajaani Oy was amalgamated into United. In 1990, Rauma Oy, Rosenlew Oy and United Paper Mills Ltd merged to become Repola Oy. In September 1995 the news was published about the merger of Kymmene Oy and Repola Oy to form a company which would take the name UPM-Kymmene Ltd.